Aug 20, 2024 | 3 mins

Crackle quartz

What is Crackle Quartz?

Crackle Quartz is quartz that has been subjected to a thermal shock process, causing it to crack. The quartz is heated to a high temperature and then rapidly cooled, which creates a network of fine cracks throughout the stone. These cracks can be enhanced by adding color or other treatments.

Treatments for Crackle Quartz

Dyeing: To enhance the appearance of crackle quartz, it can be dyed. This is done by soaking the crackled quartz in dye solutions. The dye penetrates the cracks and gives the stone a vibrant, colored appearance.

Reference photo from Google Photo

Aug 20, 2024 | 5 mins

A Paraiba tourmaline

“A Paraiba tourmaline is a blue (electric blue, neon blue, violet blue), bluish green to greenish blue or green tourmaline, of medium-light to high saturation and tone (relative to this variety of tourmaline), mainly due to the presence of copper (Cu) and manganese (Mn) of whatever geographical origin. The name of the tourmaline variety „Paraiba‟ is derived from the Brazilian locality Paraíba where this gemstone was first mined.”

‘Paraiba’ tourmaline is a famous colored stone that typically possesses strikingly beautiful bright blue color or the so-called ‘electric or neon blue’. Because of its attractive color this type of tourmaline in one of the

most sort-after stones that usually command very high price in the trade. Being driven by the market demand, many confusions and misuse of identification report have arisen in the market due to the unclear definition of ‘Paraiba’ tourmaline and other copper bearing tourmalines, some traders may assume that all copper bearing tourmalines can be called ‘Paraiba’ while some may still stick to the locality-specific name where it was first mined that the ‘Paraiba’ tourmaline has to originate from Brazil only. To clarify these confusions, GIT as the national gem institute and a member of LMHC (Laboratory Manual Harmonization Committee) would like to release this fact sheet to everyone who involve in this matter The ‘Paraiba’ is presently being considered as a variety-name of an exotic color tourmaline, green to blue, in which its color is due to the presence of copper (and manganese) as important trace elements in its structure regardless where it is originated from. The name ‘Paraiba’ derived from its original mines in Batalha region of Brazil. Apart from Brazil, there are also some other localities such as Nigeria and Mozambique, where there have been reported as being the important sources of copper-bearing tourmaline. In fact, Mozambique, in particular, has become the world largest supplier of copper-bearing tourmaline in the last few years. Most

‘Paraiba-type’ tourmalines from every sources are commonly heat-treated, especially those having purplish blue shade in order to remove the pink hue from the stone and leaving the stone more preferred blue.

Reference photo from Google search

Reference from https://git.or.th/.../2012/paraiba_fact_en_final_web.pdf

Jul 30, 2024 | 3 mins

Spinel

Spinel is a fascinating gemstone with a lot of unique qualities. Here's a detailed overview:

Composition and Formation

• Chemical Formula: Spinel is a group of minerals with the general formula [AB2O4][AB_2O_4][AB2​O4​], where AAA is typically magnesium, iron, or zinc, and BBB can be aluminum, chromium, or other metals.
• Crystal System: Cubic
• Formation: Spinel forms in metamorphic rocks, often in high-temperature and high-pressure environments. It can also be found in alluvial deposits.

Appearance

• Color: Spinel comes in a variety of colors, including red, blue, pink, purple, orange, and even black. The most prized colors are vivid red (often mistaken for ruby) and deep blue.
• Transparency: It can be transparent to opaque.
• Luster: Spinel has a vitreous (glass-like) luster.
• Hardness: On the Mohs scale, spinel ranks 8, making it quite durable and suitable for various types of jewelry.

Properties

• Refractive Index: Typically ranges from 1.718 to 1.732.
• Specific Gravity: Ranges from 3.58 to 3.63, depending on the exact composition.
• Cleavage: Spinel has no cleavage, which contributes to its toughness.
• Fracture: It typically has a conchoidal fracture.

Origin and Sources

• Main Sources: Major deposits are found in Myanmar (Burma), Sri Lanka, Tanzania, and Vietnam. Spinel can also be found in parts of Thailand and the Himalayas.
• Notable Locations: Some high-quality spinels are also found in Madagascar and the Skardu region of Pakistan.

Uses

• Jewelry: Spinel is valued for its vibrant colors and durability. It's used in various types of jewelry, including rings, earrings, and necklaces.
• Industrial Uses: Less commonly, spinel is used in refractory materials and ceramics due to its high melting point and stability.

Historical and Cultural Significance

• Historical Misidentification: Historically, spinel was often mistaken for ruby, especially in the case of some famous gems like the "Black Prince's Ruby," which is actually a large red spinel.
• Cultural Value: Spinel has been cherished in various cultures for centuries, especially in regions where it is found naturally.

Care and Maintenance

• Cleaning: Spinel can be cleaned with mild soap and water. Avoid harsh chemicals and ultrasonic cleaners, which might damage the stone.
• Storage: Store spinel separately from other gemstones to prevent scratching, and keep it in a soft cloth or padded jewelry box.

Spinel’s wide range of colors and impressive hardness make it a versatile and attractive option for gemstone enthusiasts and jewelers alike.

Photo credit from Gorgeous Pink Spinel Gemstone from Sri Lanka, 1.45 cts., 8x6 mm., Oval Shape (kosnargemco.com)

Reference from Mindat.org