TANZANITE and OTHER ZOISITES USED IN VINTAGE JEWELRY AND CONTEMPORARY ESTATE JEWELRY
BIRTHDAYS AND ANNIVERSARIES
Tanzanite is the suggested gemstone to celebrate 24th wedding anniversaries.
ORIGIN OF NAME
The name tanzanite was given to the gemstone by Henry B. Platt, vice-president and director of Tiffany and Co. The name was made after the country where the stone is found, Tanzania. Tiffany and Co. is the firm that generated a market for this gemstone.
VIEW OUR CONTEMPORARY ESTATE TANZANITE JEWELRY COLLECTION
Incredible Tanzanite and Baguette/Round Diamond 14KT White Gold Estate Ring
Ash Tanzanite Opal Gold Ring
HISTORY
Zoisite was mentioned in 1905, the pink variety from Norway was used as ornamental stones for cabochons and carvings. In 1967, an intense blue variety from Tanzania was found and marketed by Tiffany and Co. After this time, tanzanite has become very popular as a faceted gemstone.
LEGENDS
As zoisites and tanzanites are relatively new gemstones there are not really any legends.
AREAS FOUND
Tanzanite was first discovered at the foothills of Mount Kilimanjaro in Africa in the 1960s. Henry Platt, vice-president of Tiffany's named the stone after Tanzania, the country where tanzanite is found.
HARDNESS
With a hardness of 6 to 7, on the Mohr's Scale, tanzanite's toughness is considered fair to poor. It is not recommenced for wedding jewelry or daily wear. Almost all tanzanite is heated to remove brownish and yellowish colors.
ESTATE JEWELRY CARE INSTRUCTIONS
Ultrasonics, steamers, abrupt temperature changes and rough wear should be always be avoided. Avoid acids and chemicals.
EVALUATIONS
Most consider that a deep blue with a faint purple secondary color to be the most favorable. Blue stones are worth more than purple. Light lavender stones are valued the least. Prices also vary depending on size quality and availability. High clarity and transparency add to its value.
VARITIES OF TANZANITE :
TANZANITE: ranges in colors from deep blue with a faint purple, to lavender. Generally heat produced to remove the brownish tones.
THULITE: used for cabochons or carvings, also called rosaline. Found in Norway, Australia, Italy, Austria, and the US.
GREEN, YELLOW, ORANE OR PINK TRANSPARENT ZOISITE: harder to find varieties
GREEN ZOISITE: often found with rubies, zoisite is frequently carved
TECHNICAL DATA
Crystal system: orthorhombic
Cleavage: perfect in one direction
Refractive Index: 1.69 - 1.70
Optic: double refracting and biaxial positive
Specific Gravity: 3.20 - 3.40
MOHR's SCALE
The measure of relative hardness, Mohr's Scale defines common stones and minerals for the hardness and durability. Hardness is one measure of the strength of the mineral relative to its chemical bonds. It is not the same as brittleness, which is related to the structure of the mineral. Hardness is tested by scratching. Using Mohr's Scale, the higher the number, the harder the mineral. talc (used to write on chalkboards) is defined as the softest mineral and is given the value of 1. Diamonds are the hardest and are given the value of 10.
Mohr's Scale is as follows:
1. Talc
2. Gypsum - a fingernail is 2.5
3. Calcite
a copper penny
4. Fluorite
5. Apatite
window glass
6. Orthoclase
a good steel knife
6 to 7 Tanzanite
7. Quartz - Citrine - Amethyst
8. Topaz
9. Corundum - rubies - sapphires
10. Diamond
SPECIFIC GRAVITY
The specific gravity is the ration of the density of an object when compared to water. In the simplest testing, it is simply the weight of a mineral compared to its volume. The volume of the stone is measured by the amount of water in displaces.
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