Joined: Sun Oct 16, 2005 12:22 pm Posts: 21602 Location: San Francisco
Hi Macvan. If we look at the definition of goldstone you'll see that "natural goldstone" would be a misnomer. Goldstone is defined as glass which incorporates included copper crystals.
Wikipedia wrote:
The original manufacturing process for goldstone was invented in seventeenth-century Venice by the Miotti family, which was granted an exclusive license by the Doge. Urban legend says goldstone was an accidental discovery by unspecified Italian monks or the product of alchemy, but there is no pre-Miotti documentation to confirm this.
The most common form of goldstone is reddish-brown, containing tiny crystals of metallic copper that require special conditions to form properly. The initial batch is melted together from silica, copper oxide, and other metal oxides to chemically reduce the copper ions to elemental copper. The vat is then sealed off from the air and maintained within a narrow temperature range, keeping the glass hot enough to remain liquid while allowing metallic crystals to precipitate from solution without melting or oxidizing.
After a suitable crystallization period, the entire batch is cooled to a single solid mass, which is then broken out of the vat for selection and shaping. The final appearance of each batch is highly variable and heterogenous. The best material is near the center or "heart" of the mass, ideally with large, bright metal crystals suspended in a semitransparent glass matrix.
Indian sunstone (despite the lack of actual copper) is not a bad match for appearance (it looks much better imo but it's a similar color and also sheeny).
Joined: Thu May 03, 2007 1:19 am Posts: 370 Location: Pakistan
Dave , The dealer showed me a report of some private lab , regrettably I did not take a pic of it , he also had some papers saying the mtrl had been put on display on last Hong Kong show.
I had no interest beyond curiosity and saw the stones on my last day in Bangkok with clock ticking a little faster than normal so just took pics of the stones.
In case you have an interest I can send you his contact and you can ask him directly.
It's just essentially bronze/black star sapphires--flat faces will show a sheen rather than a legged star. I have some rough that would cut similar (but inferior) stones.
Users browsing this forum: No registered users and 13 guests
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot post attachments in this forum