 April 2011
In our newsletter this month:
• Kyanite from Nepal
• New and Interesting Gemstones
• Rare and Unusual Gems
• Customer Questions
Kyanite from Nepal
Some rare and wonderful gemstones have been found in the region of the world's highest mountains, from the Himalayas to the Hindu Kush. The most famous include the legendary blue sapphires from Kashmir and the balas rubies (spinels) of Badakshan in Afghanistan.
Though the Kashmir sapphires and the Badakshan spinels have long been exhausted, the region has vast mineral reserves. Last month we wrote about the very fine emeralds discovered in Afghanistan. Another recent discovery is kyanite from Nepal, now widely regarded as the finest kyanite in the world.
 Kyanite is an aluminum silicate with the same chemical composition as the gemstones andalusite and sillimanite. But kyanite has a different crystal structure and thus different physical properties. One of the unusual properties of kyanite is that it has a variable hardness -- it is fairly soft when cut parallel to the long axis of the crystal, with a hardness of only 4 to 4.5 on the Mohs scale . But it has a hardness of about 6.5 when cut perpendicular to the long axis.
The interest in kyanite as a gemstone derives from the fact that the best specimens shows a sapphire-like blue. But this color is rarely found and most kyanite displays a watery blue with a color that is typically not consistent throughout the crystal and can be blotchy or in streaks.
However, recent finds of very high quality kyanite in Nepal are changing perceptions of this gem. Where the kyanite from Cambodia and Burma only rarely delivers on the promise of a sapphire-like blue, the Nepalese material sometimes comes surprisingly close to the velvet blue of the best Ceylon and Madagascar sapphires.
Miners in Nepal first discovered high quality kyanite in 1995. According to the Nepalese mining department, four small-scale kyanite mines are currently in operation. Production is very limited and will probably remain so. Generally kyanite is not found in large sizes, and a 2 carat stone would be considered a very good size.
We have just acquired a significant parcel of Nepalese kyanite, with more than 300 pieces in stock. There are some very fine round stones, many of which bear a striking resemblance to sapphire, as well as an outstanding pear shape stone over 10 carats. |
