Course:EOSC311/2024/Crust to Consumer: The Production and Distribution of Sapphires

From UBC Wiki

Overview

Picture of a large rough sapphire/corundum.
Rough corundum (sapphire)

Sapphires are precious gemstones that are primarily composed of aluminum oxide (Al₂O₃) and are derived from the mineral corundum.[1][2] While best known for being blue in colour, sapphires can be found in a wide array of hues including pink, yellow, green, and purple.[1][3] Red corundum is known as a different gemstone called ruby, although the two gems are essentially composed of the same material and have the same physical and optical properties.[4][5] Sapphire has been highly valued for its beauty, durability, and perceived magical and medicinal properties all throughout history.[1]

Today, sapphire is still a greatly valuable resource, playing a crucial role in various modern industries and technologies. Sapphire has a Mohs hardness rating of 9, making it highly scratch-resistant and durable.[1] It is resistant to chemical corrosion and extreme heat, and its high refractive index and transparency provide it with a unique luster.[1] These properties make sapphire a versatile and useful gem for various applications. Additionally, sapphire has excellent thermal conductivity, making it valuable in electronic component manufacturing.[1]

Statement of Connection

In EOSC 311, we looked at the geological processes surrounding various resources, including the formation, valuation, and distribution of diamonds. Through studying the process of bringing these precious minerals from the mine to the market, I became intrigued about the formation and supply chains of other gemstones. As a Commerce major specializing in Operations and Logistics, I chose to focus on reporting the production and distribution of sapphire since it demonstrates relevance regarding both operational and geological concepts.

Understanding the geological formation and location of sapphires is crucial for efficient resource extraction, informing the initial prospecting and mining stages of the supply chain. The geological factors influencing the quality and characteristics of sapphires explain their many valuable physical properties. Sapphires are prized for both their beauty and various industrial applications. This emphasizes their significance in global commerce, reinforcing the need for well-coordinated logistics to meet the demands of different markets.

Additionally, the sapphire industry offers an in-depth case study in supply chain management. The production and distribution of these precious gemstones involves multiple steps, including mining, processing, treatment, and distribution. Each of these steps has its own logistical and ethical challenges. There are numerous global players involved, from miners in Madagascar and Australia to cutting and polishing centers in Thailand and China. This illustrates how raw materials are sourced from various parts of the world and eventually sold as end products. Analyzing the challenges and processes in the supply chain, including sourcing, transportation, market fluctuations, and ethical considerations, is essential in creating efficient and sustainable supply chains. This is a fundamental aspect of my field and a critical component of effective supply chain management.

Geological Formation of Sapphire

How Sapphires Form

Geological diagram of sapphire-bearing minerals being formed by a hydrothermal fault cutting across layers of basalt and other rocks.

Corundum (ruby and sapphire) often develops deep within mountainous and volcanic regions.[1][2] It can form in igneous rocks like basalt and syenite, as well as metamorphic rocks like schist and gneiss.[1][5] Igneous rocks result from the crystallization, cooling, and solidification of magma, while metamorphic rocks are formed from preexisting rocks that are altered by heat and pressure over time.[1] The slower the cooling process of corundum in the magma, the larger the resulting sapphires.[2] Tectonic activity helps create the right pressure and temperature conditions for corundum to form.[1]

Corundum forms in environments that are both rich in aluminum low in silicon.[4] As such, alkaline basalt is a common rock type that facilitates corundum formation.[4] Partial melting of the lithosphere due to rising mantle plumes can cause eruptions of this basalt.[4] Sapphires also develop in crustal metamorphic rocks that are low in gallium and contain no quartz.[4]

Additionally, some sapphires form through hydrothermal processes, where molten, mineral-rich fluids flow through cracks and fissures in rocks.[1] These are referred to as hydrothermal veins and are usually found around hot springs and volcanic vents.[1]

Types of Sapphire Deposits

Primary Deposits

Primary deposits are found within uneroded igneous and metamorphic rocks, the original geological setting where sapphire forms.[1] These deposits often include other minerals like emerald and diamond.[1]

Direct mining of sapphire from primary deposits is uncommon because extracting small gems from hard igneous and metamorphic rocks is generally uneconomical.[5] Plus, a large amount of rock would be damaged during the mining process.[5]

Secondary Alluvial Deposits

Alluvial deposits form when sapphire is deposited in sedimentary layers after being eroded from its original setting and transported by rivers to new locations.[1] These deposits are generally formed in terraces, riverbeds, and floodplains.[1] Alluvial deposits can be easily extracted using simple hand tools like shovels and pickaxes.[1]

Secondary Eluvial Deposits

Eluvial deposits are typically smaller, as well as harder to extract and locate, in comparison to alluvial deposits.[1] Eluvial deposits occur when sapphire is eroded from its primary geological setting and found in the soil and weathered rock at the base of slopes.[1]

Economic sources of corundum are primarily found in secondary deposits, particularly in alluvial deposits.[5] As igneous rocks weather and erode, the tougher and more resistant minerals like corundum remain in the rock.[5] These durable minerals become concentrated in the landscape as they're continuously transported by streams over time, making these deposits easier to source and mine.[5]

Colours of Sapphire

Sapphires divided by their colour distribution, shape and size.
Sapphires divided by their colour distribution. The different shades of blue are influenced by the amount of titanium oxide and iron oxide present in the gem's crystal structure. The colourless sapphire is pure corundum.

Colour is the greatest factor when assessing the market value of a sapphire.[6] Every large sapphire deposit forms with a unique colour and look.[2] This is due to the differences in environmental factors and pressure as the molten magma cools.[2] Corundum can occasionally contain inclusions of crystal needles, producing gems with asterism, commonly called "star sapphires" or "star rubies."[5] This effect is named after the star-like pattern that the crystal needles reflect on the gem's surface.[5]

Sapphires come almost all colours of the rainbow, and can also be multicoloured or two-toned.[3][6] The colour of the gem is controlled by the impurities that infiltrate the corundum's crystal lattice during the gemstone's formation.[4][5] Different trace elements produce different colours, although the amount of the trace elements are usually less than 3%.[4] Multicoloured sapphires are created due to uneven temperature changes or distribution of trace elements while the corundum is formed.[6]

Trace Elements and Their Resulting Colours

  • Vanadium: colour-shifting[6]
  • Ferrous iron oxide: yellow[3][4]
  • No trace elements: white/colourless[3]
  • Ferric iron oxide and titanium oxide: green[3][4]
  • Low concentration of chromium oxide: pink[3]
  • High concentration of chromium oxide: red (ruby)[3][4]
  • Chromium oxide and ferrous iron oxide: orange[3][4]
  • Titanium oxide and ferrous iron oxide: blue[3][4]
  • High concentration of titanium oxide and ferrous iron oxide: black[3]
  • Chromium oxide, ferrous iron oxide, titanium oxide, and vanadium: purple[3][4]

Geographical Sources of Sapphire

Map of common locations of sapphire deposits across the world highlighted in blue.
Common locations of sapphire deposits: Sri Lanka, India (Kashmir), China, Vietnam, Thailand, Madagascar, Myanmar (Burma), Greenland, Kenya, Tanzania, Malawi, the United States (Montana and North Carolina), Laos, Cambodia, and Australia.

There are several sources of sapphire from all over the world. The traditional sources, which have been actively producing corundum for centuries, include countries and regions such as Kashmir, Myanmar (Burma), Sri Lanka, and Thailand.[1][7] Recently, the corundum production from these sources has fluctuated greatly, and political concerns have sometimes limited the gemstone's global market distribution.[7] Many large modern sources of corundum originate from Australia, Madagascar, and Vietnam, while smaller deposits are found in Cambodia, Laos, China, Greenland, Kenya, Tanzania, Malawi, Central Asia, and the United States.[7]

Notable Sapphire Deposits

Kashmir

Classic Kashmir sapphires are widely considered the rarest and most valuable coloured gems due to their famous velvety blue colouration.[7][8] These gems are highly sought after, commanding exorbitant prices in the gemstone market, but the discovery of new Kashmir sapphires is very rare.[7] Classic Kashmir sapphires were discovered in 1881 after a landslide in the Zanskar mountain range in the Himalayas uncovered the gems.[7][8] The few sapphires mined in Kashmir today usually don't exhibit the same cornflower blue as their predecessors.[7]

Myanmar (Burma)

Myanmar is one of the world's leading producers of corundum, with the Mogok region in the north of the country being especially renowned for its ruby deposits.[7][9] Although rubies are more commonly found in Mogok, accounting for about 80-90% of the total output, sapphires from this region can reach larger sizes.[9]

However, the trade in Myanmar corundum has faced significant challenges due to international sanctions. In response to human rights abuses and political unrest in Myanmar, the United States and the European Union have imposed bans on the import of gemstones from the country.[7] This led to a decrease in corundum's availability on the international market, driving up prices and increasing its desirability from alternative sources.[7]

Picture of a padparadscha sapphire, which has an orange-pink colouration.
Padparadscha sapphires are prized for their unique pink-gold colouration and have been historically sourced from Sri Lanka.

Sri Lanka

Sri Lanka has historically been a major source of corundum, particularly known for its alluvial sapphire deposits.[1][10] This country has been a prominent source of valuable variants of corundum, including star sapphires and the highly prized padparadscha sapphires, which exhibit a unique blend of pink and orange hues.[7][10] In recent years, however, the availability of sapphires in Sri Lanka has declined.[7]

Thailand

Thailand has historically been a significant producer of sapphires, though the extraction of its sapphire deposits has been steadily declining since the 1990s.[1][7] Instead, the Thai gemstone industry shifted its focus to purchasing corundum from other countries and enhancing these gems through treatment processes.[7] As a result, Thailand processes and cuts approximately 70% of the world's sapphires, which are then traded in local markets and exported globally.[7]

However, recent advances in gemstone treatment techniques, along with embargos, economic downturns, and political instability, have significantly impacted Thai sapphire exports.[7]

Australia

From the 1970s to the 1990s, Australian corundum deposits supplied approximately 70% of the world's sapphires.[5][7] Australia was also a significant producer of corundum prior to World War I.[7] Australian sapphires are typically known for their darker hues, which are often less desirable in the market.[7] However, these sapphires were able to undergo color correction by being treated in Thailand, enhancing their appeal and marketability.[7]

Madagascar

Over the past 20 years, Madagascar has emerged as the world's leading supplier of corundum.[1][7] High-quality blue sapphires were discovered in the Andranondambo and Antsiranana regions in the 1990s, where several large corundum deposits were found one after another.[7]

A significant amount of sapphires were smuggled out of Madagascar, so statistics on its worldwide production are often contradictory.[7] However, it is estimated that by 2005, Madagascar was responsible for producing between 25-50% of the world's sapphires.[7]

Mining and Extraction Process

Primary Deposits

Picture of a large open pit mine.
Open pit mining in Australia.

Primary deposits, deep within mountains and volcanic regions, require large-scale, industrial mining techniques for extraction.[1][11] Accessing these minerals often involves using drilling, blasting, and open pit mining techniques to reach the corundum deposits.[1][5]

Geological surveys are first used to identify and evaluate potential mining sites.[12] Once a site is confirmed, drilling rigs create deep holes in the rock, and explosives are strategically detonated to destroy the rock and extract the corundum-containing ore.[12]

Then, excavators and haul trucks are used to transport the ore to processing facilities.[12]

Secondary Deposits

Alluvial deposits

Most alluvial sapphire deposits are mined through artisanal and small-scale mining (ASM) techniques.[1][13] ASM is the primary extraction technique in the gemstone industry since it can be executed with simple tools, does not require much specific knowledge, has fast and high returns, and attracts a large amount of workers.[11]

Artisanal miners typically work in riverbeds, manually sifting through the alluvial sediments using shovels and sieves to separate the sapphires from the other materials.[1] The simple and low cost nature of ASM makes it a popular extraction technique in remote and rural communities.[13]

Eluvial deposits

Eluvial deposits are generally more challenging to mine than alluvial deposits since the gemstones are trapped within rocks at the base of mountains.[1] In some African and South American countries, eluvial deposits are extracted using hydraulic mining techniques.[5] This method involves using high-pressure water to wash away sediments on cliff faces and mountains, exposing the gemstone ore underneath.[14] However, many gem buyers boycott companies that employ hydraulic mining because it has significant repercussions on the local environment, stripping the topsoil from the area.[5]

Processing and Refining Process

Image of a trommel used to sort sapphires by size.
Trommel used to sort sapphires by size.

Cleaning and Sorting

Once mined, corundum-bearing ore is loaded in steel drums and transported to sorting and processing facilities.[13] Corundum is heavier and denser than other sediments, so it can be easily separated from clay and gravel.[5][15] Typically, the gravels are broken up using rotating drums (trommels) and high pressure water jets that pass over filters with holes of various sizes.[5][15] The trommel sorts the material by size, passing it through progressively coarser meshes.[15] The heavier gravel sinks, while lighter materials, like clay, get washed away.[5][15]

After sifting out the gravel and clay, the corundum concentrate still contains heavy minerals like magnetite and zircon.[5] Magnetite is removed using both handheld magnets and magnetic separators, while zircon is manually extracted.[5][15] Then, the sapphires are graded based on size and colour, which determines the level of treatment they need to receive.[15]

Treatment

Treatment is a widespread practice in the sapphire industry, used to enhance or refine the colour and clarity of the gemstones.[15] Sapphires may undergo heat treatment or be treated with various substances to remove impurities or fill in imperfections.[1][6][16] It is mandatory for sapphire suppliers and retailers to disclose any treatments that the sapphires have undergone.[17]

Heat Treatment

Heat treatment is often used to alter the colour and clarity of sapphires.[1][16]

This process can changes a sapphire's colour by manipulating the oxidation states of the trace elements responsible for its hue.[16] For example, to make a sapphire darker, the trace element must be in a less oxidized state.[16] Converting ferric iron (Fe3+) to ferrous iron (Fe2+) will result in a darker blue sapphire.[16] In contrast, increasing the oxidization of the trace element will result in a lighter colour (i.e., converting Fe2+ to Fe3+ will result in a lighter blue sapphire).[16]

Heat treatment can also enrich the colour and clarity of a sapphire by dissolving certain impurities.[1] Intense heat can also allow the colour-causing trace elements to become more evenly distributed throughout the gem, removing unwanted patches of colour.[16]

Diffusion Treatment

The colour of a sapphire can be enhanced by introducing additional colour-causing trace elements to its surface.[16] To create an enriched blue colour, sapphires are heated to temperatures near their melting point and exposed to iron and titanium oxide powders.[16] This allows the trace elements to diffuse into the gemstone's surface.[16] This is a slow process, so the trace elements only penetrate the surface layer of the gem, creating a vibrant and smooth finish.[16]

Picture of a person cutting a gem at a workbench.
Gem cutting and polishing (lapidary) in Thailand.

Lead-Glass Filling

Sapphires may also be filled with high lead-content glass to fill in any fractures or inconsistent surfaces on the gem.[1][6] This improves the stone's clarity.[1][6] Lead glass has a high refractive index, making the filled cracks harder to detect with the human eye.[7]

Cutting, Shaping, and Polishing

Sapphires used for jewelry and ornaments are cut, shaped, and polished through a process called lapidary.[13] This can be done either locally in the country where the stones are sourced or in one of the global cutting hubs.[11] Governments from countries that produce gemstones are increasingly encouraging local cutting to retain more value from the stones within the country.[11] However, most modern cutting and polishing takes place in global cutting centers such as India, Thailand, or China.[11]

Manufacturing and Marketing

Marketing and Trading

Before reaching retailers and manufacturers, gemstones typically pass through 10-15 intermediaries, including traders, dealers, brokers, suppliers, collectors, and importers.[13][11][18] This means that the gemstones undergo an extremely long supply chain, and by the time they reach retailers and consumers it may become impossible to know which country or mine the gemstones originated from.[18] The lack of traceability in the supply chain exposes the industry to unethical sourcing and mining practices.[18]

Industrially Mined Stones

Large-scale industrial miners tend to have a shorter and more formalized supply chain, with a significantly lower amount of intermediaries.[11] Industrial mines primarily sell rough sapphires through direct contracts or spot sales.[15] Contracts are usually six-month agreements between miners and buyers, where the buyer purchases the miner's entire production at a negotiated price.[15] These contracts are renewed every six months.[15] Alternatively, sapphires can be sold on the spot to travelling buyers, though this method is less preferred.[15] Miners and wholesalers also purchase and sell sapphires at trade shows and auctions, where they display and sell their current inventories.[13][11]

The typical supply chain for artisanally mined stones is long and complex, with gems passing hands between several intermediaries before reaching retailers and consumers.

Artisanally Mined Stones

Artisanally mined stones often have a longer supply chain involving several intermediaries.[11] This is partially because these stones are mined in remote areas and under informal circumstances.[11] As such, it would be difficult for jewelry companies and international wholesalers to buy stones directly from these mines.[11] Additionally, miners may not be able to reach the international markets themselves, either because they cannot physically reach the trading centers or because they are bound by legal obligations regarding their mining licenses.[11]

Usually, after sapphires are mined using ASM techniques, the miner passes the stones to a broker, who sells their gemstones on their behalf.[18] Usually, the broker sells the stone with a high markup, only compensating the miner with a tiny portion of the selling price.[18] The broker then sells the gemstone to a rough gemstone dealer, who sends it to a cutter.[18] At this stage, the gemstone is usually exported to a global cutting center, such as Thailand, because it's cheaper to outsource the labour than cut the gems locally.[18] Then, the gemstone is passed through more traders, brokers, wholesalers, and dealers before it eventually reaches a jewelry designers and retailers.[18]

However, exceptions to this supply chain exist for large and high-quality stones. These stones are more desirable in the market, so international wholesalers and traders will try to obtain them as soon as possible.[11] Shorter supply chains benefit these wholesalers since they are able to keep intermediaries from cutting into their profits, effectively keeping their margins high.[11]

Manufacturing

After gemstones reach retailers and jewelry designers, they move on to the manufacturing stage. During this phase, the sapphires are crafted into jewelry, watches, and other items.[11][13] Most luxury jewelry brands prefer to handle manufacturing in-house, though it can also be outsourced to other parties.[11] For highly valuable sapphires, manufacturing typically takes place closer to the jewelry retailer, both organizationally and geographically.[11] However, this proximity is less important for sapphires that are not intended to be used for luxury jewelry.[11]

Retail and Industrial Applications of Sapphire

Finished sapphires are transported to retail stores or used for industrial purposes, with the resulting products being sold to end consumers. Sapphires have various applications in both retail and industrial sectors.

Picture of an ornate sapphire necklace.
Sapphires are popular gems used in luxury jewelry due to their association with royalty and rarity.

Jewelry

Sapphires have been featured in jewelry since ancient times, first being used by the Babylonians, Egyptians, Greeks, and Romans.[19] They gained extensive popularity after being featured in European royal jewels throughout the 1700s, and their recognition as high-end jewels was bolstered by Princess Diana's engagement ring in 1981.[19] Known for their attractive colours, durability, and association with wealth, sapphires are desirable gemstones for jewelry and ornaments.[1][5]

Windows and Optics

Sapphire's high transparency, hardness, and scratch resistance makes it an ideal material for the cover glass on wristwatches, smartphone lenses, and fingerprint readers.[1][20] Sapphire's ability to withstand high temperatures, pressures, and chemical exposure also makes it useful for observation windows in testing equipment and space vehicles.[20] In scientific and industrial applications, sapphires are used in lasers, high-pressure cells, prisms, and bulletproof glass.[1]

Industrial and Medical Tools

Sapphire is used in a variety of industrial tools such as grinding wheels and various abrasive powders.[5] Its hardness allows it to cut, grind, and polish other materials with ease.[1][5] Sapphire is also biologically compatible in the sense that it does not trigger negative reactions when in contact with human tissue.[21] This, paired with the gemstone's chemical stability, makes it a valuable material for a variety of surgical applications.[21] It is used in scalpels, dental tools and endoscope lenses, offering high-quality images with minimal distortion in endoscopic surgery.[1][21]

Semiconductors and Electronic Components

Sapphire is a valuable substrate for electronic components like LEDs, power transistors, and integrated circuits in semiconductor manufacturing due to its excellent electrical insulating properties.[1][20] It is crucial for various semiconductor manufacturing parts, including carrier plates, wafer handling arms, liquid transport rods and tubes, and lift pins.[20]

Issues Regarding the Supply Chain of Sapphires and Other Coloured Gemstones

Each step of the sapphire and gemstone supply chain is exposed to its own set of ethical and governance issues. These issues include human rights abuses, poor working conditions, environmental damage, and criminal activities, which are perpetuated by a lack of traceability.[11]

Unethical Mining and Manufacturing Practices

Artisanal and small-scale mining (ASM) accounts for at least 80% of sapphire production.[22] These operations often function under informal and unregulated conditions, leading to severe ethical and safety issues.[11][22] Miners, including children, often work in hazardous environments such as underground mines.[22] For example, in Madagascar, children help sort and wash minerals, and then begin entering the mines by the age of 15.[23] Child labour is also used in countries such as Mozambique, Tanzania and Zambia.[22] Miners also face health and safety concerns, such as blindness and shorter life expectancy, as a result of poor working conditions and the use of toxic chemicals.[11] In Madagascar, miners often descend 30 meters into narrow, unsecured holes.[11] Furthermore, while the final sapphire products are often sold at exorbitant prices by luxury retailers, the miners at the beginning of the supply chain barely receive compensation.[23] This perpetuates a cycle of poverty and exploitation in mining regions.

Environmental Risks

The rush for sapphires in Madagascar has led to significant environmental damage, as mining often illegally occurs in environmentally protected areas.[11] The lack of local governance means that there is little to no regulation surrounding the remediation and rehabilitation of mining sites.[11] Abandoned mining holes are hazardous to wildlife and humans, and also contribute to soil erosion, changes in river flow, and water contamination.[11] Additionally, the use of mercury when cleaning and washing stones also causes environmental damage by seeping into the local soil and water.[11]

Lack of Traceability

The lack of traceability in the sapphire industry perpetuates these ethical issues. Sapphires often pass through numerous intermediaries before reaching consumers, making it challenging to verify the origins of the gemstones and ensure ethical sourcing.[11] This complex supply chain also allows intermediaries to use bribes and fraud to sell gems for a large profit, bypassing official regulations.[23] This allows for the continued circulation of unethically produced gems and makes it challenging to fix existing issues in the industry.[11] The lack of transparency also allows for the misrepresentation of gemstones to retailers and consumers.[18] Retailers often falsely claim that their jewels are ethically sourced, relying on the word of their dealers without the means or due diligence of verifying the gemstone's origins.[18]

Conclusion / Evaluation of the Connections

In conclusion, sapphires are highly treasured gems, both for their beauty and their useful physical properties. This makes them valuable resources that are used in a variety of decorative and industrial applications. Analyzing the geological formation and supply chain of sapphires showcases the processes and challenges involved in extracting these gemstones from the Earth and selling them to the market. Understanding these aspects of sapphire production and distribution is essential in both geological and commercial contexts, allowing for the efficient extraction and valuation of these gems. The mining, processing, and distribution of sapphires also reveals the various logistical and ethical considerations associated with delivering these gems to end consumers.

Analyzing the production and distribution of sapphires is relevant to operations and logistics professionals as it offers crucial insights into the gemstone industry, particularly in regards to its various ethical issues. The sapphire supply chain currently faces significant ethical and environmental concerns, particularly within artisanal and small-scale mining operations. Issues involving human rights violations, criminal activities, and environmental degradation run rampant, perpetuated by a lack of transparency in the industry. As such, the sapphire supply chain acts as a relevant case study for business professionals, demonstrating the importance of responsible supply chain practices in commerce. It also reinforces the role of logistics in not only creating optimal and efficient supply chains, but also in promoting ethical and sustainable practices that benefit all stakeholders.

References

  1. ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 1.16 1.17 1.18 1.19 1.20 1.21 1.22 1.23 1.24 1.25 1.26 1.27 1.28 1.29 1.30 1.31 1.32 1.33 1.34 1.35 1.36 1.37 1.38 Sapphire. Geology Science. (2023, April 24). https://geologyscience.com/gemstone/sapphire/?amp
  2. ↑ 2.0 2.1 2.2 2.3 2.4 Das, S. (2022, July 29). Formation of the sapphire gemstone. Medium. https://das-sushan007.medium.com/formation-of-the-sapphire-gemstone-27e25a80373f
  3. ↑ 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 The different colors of sapphires. Earth’s Treasury. (2021, February 18). https://www.earthstreasury.com/2021/02/18/the-different-colors-of-sapphires/
  4. ↑ 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 4.11 4.12 University of Nebraska - Lincoln. (n.d.). Traditional birthstones - sapphire (September). Institute of Agriculture and Natural Resources. https://snr.unl.edu/data/geologysoils/birthstones/sapphire.aspx
  5. ↑ 5.00 5.01 5.02 5.03 5.04 5.05 5.06 5.07 5.08 5.09 5.10 5.11 5.12 5.13 5.14 5.15 5.16 5.17 5.18 5.19 5.20 5.21 Australian Government. (2023, September 4). Sapphire and ruby. Geoscience Australia. https://www.ga.gov.au/education/minerals-energy/australian-mineral-facts/sapphire
  6. ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 Akmakjian, R. (2023, January 9). Everything you need to know about sapphires. BriteCo. https://brite.co/blog/everything-you-need-to-know-about-sapphires/
  7. ↑ 7.00 7.01 7.02 7.03 7.04 7.05 7.06 7.07 7.08 7.09 7.10 7.11 7.12 7.13 7.14 7.15 7.16 7.17 7.18 7.19 7.20 7.21 7.22 7.23 7.24 Shor, R., & Weldon, R. (2009). Ruby and sapphire production and distribution. Gemological Institute of America. https://www.gia.edu/doc/Ruby-and-Sapphire-Production-and-Distribution.pdf
  8. ↑ 8.0 8.1 History of Kashmir sapphires. The Natural Sapphire Company. (2019, September 13). https://www.thenaturalsapphirecompany.com/blog/history-kashmir-sapphires
  9. ↑ 9.0 9.1 Hughes, R. W. (n.d.). Introduction to Burmese sapphires. Ganoksin. https://www.ganoksin.com/article/introduction-burmese-sapphires/
  10. ↑ 10.0 10.1 Ministry of Investment Promotion. (n.d.). Sri Lanka; the sapphire capital of the world. Sri Lanka Export Development Board. https://www.srilankabusiness.com/gem-diamond-and-jewellery/about-sri-lanka-gems/ceylon-sapphire.html
  11. ↑ 11.00 11.01 11.02 11.03 11.04 11.05 11.06 11.07 11.08 11.09 11.10 11.11 11.12 11.13 11.14 11.15 11.16 11.17 11.18 11.19 11.20 11.21 11.22 11.23 11.24 11.25 11.26 11.27 Collet, L., Curtze, L., & Reed, K. (2013, December 15). Responsible sourcing of colored gemstones. https://www.responsiblejewellery.com/wp-content/uploads/Responsible-Sourcing-of-Colored-Gemstones_ARS-Final-Report_-Collet-Curtze-Reed.updated.pdf
  12. ↑ 12.0 12.1 12.2 Mining industry: a complete guide. Flyability. (n.d.). https://www.flyability.com/blog/mining-industry
  13. ↑ 13.0 13.1 13.2 13.3 13.4 13.5 13.6 Rocha, A. (2021, September 16). From mine to market: The journey of our gemstones. Stonebridge Imports. https://stonebridgeimports.ca/blogs/crystal-mining-sourcing-and-selling/from-mine-to-market-the-complete-journey-of-our-gemstones
  14. ↑ Watkins, C. E. (n.d.). Hydraulic mining techniques, California, 1870s. U.S. Geological Survey. https://www.usgs.gov/media/images/hydraulic-mining-techniques-california-1870s#:~:text=Hydraulic%20mining%20was%20a%20variation,the%20miners%2C%20ounces%20of%20gold.
  15. ↑ 15.00 15.01 15.02 15.03 15.04 15.05 15.06 15.07 15.08 15.09 15.10 Sorrel, C. (2003, August 16). Sapphires - processing, grading, characteristics, heat treatment and marketing of sapphires. AZO Materials. https://www.azom.com/article.aspx?ArticleID=2117
  16. ↑ 16.00 16.01 16.02 16.03 16.04 16.05 16.06 16.07 16.08 16.09 16.10 UC Berkeley. (n.d.). Corundum. https://nature.berkeley.edu/classes/eps2/wisc/Lect8.html
  17. ↑ Treatment is not a dirty word. Gemmological Association of Australia. (n.d.). https://www.gem.org.au/treatment-is-not-a-dirty-word/
  18. ↑ 18.0 18.1 18.2 18.3 18.4 18.5 18.6 18.7 18.8 18.9 MacDougall, C. (2023, October 23). Mine to market sapphires & gemstones: What is it and why is it so important?. Gem Breakfast. https://gembreakfast.com/blogs/news/what-does-mine-to-market-mean
  19. ↑ 19.0 19.1 Are sapphire engagement rings popular?. The Diamond Reserve. (2024). https://thediamondreserve.com/engagement-rings/are-natural-sapphire-engagement-rings-popular/
  20. ↑ 20.0 20.1 20.2 20.3 Industrial applications of sapphire. Orbray. (2024, January 31). https://orbray.com/magazine_en/archives/1200
  21. ↑ 21.0 21.1 21.2 Analytical Components LLC. (2023, August 23). Synthetic sapphire selection for surgical and endoscopic applications. Surgical Robotics Technology. https://www.surgicalroboticstechnology.com/articles/synthetic-sapphire-selection-for-surgical-and-endoscopic-applications/
  22. ↑ 22.0 22.1 22.2 22.3 Letting it shine: Governance for equitable coloured gemstone supply chains. The Gemstones and Jewellery Community Platform. (n.d.). https://www.gemstones-and-jewellery.com/white_papers/letting-it-shine-governance-in-coloured-gemstone-supply-chains/
  23. ↑ 23.0 23.1 23.2 Zaugg, J. (2024, January 16). Madagascar sapphires: A blessing for Swiss jewellers, but a curse for miners. Public Eye. https://www.publiceye.ch/en/media-corner/press-releases/detail/madagascar-sapphires-a-blessing-for-swiss-jewellers-but-a-curse-for-miners


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