Monday, October 15, 2007

New Record Price Paid for a Diamond

A new record high price-per-carat was paid last week when a bidder at a Sotheby's auction paid almost $8 million dollars for a 6.04ct. diamond! At least 7 telephone bidders vied for the diamond at the auction held in Hong Kong. The stone was a flawless, emerald-cut, Fancy Vivid Blue diamond. The price beat the 20 year old record of $926,000 per carat.

Wednesday, September 05, 2007

Radioactive Topaz
I've read several articles lately saying that the Nuclear Regulatory Commission is reviewing their policy concerning irradiated gemstones. Many gemstones, including topaz is commonly irradiated to change or improve its color. Almost all blue topaz has been irradiated (and heated). If done properly, the irradiated stones should pose no threat to people wearing them. There are apparently laws in place to regulate the import of all radioactive materials. The problem seems to be that the NRC has no provisions for overseeing irradiated gemstone imports. So for the time being, they are not enforcing the laws, but are now looking into setting up some procedures and oversite. They don't believe there is any real danger to the public, but from people I've talked to there is at least the possibility that gemstones could come into the country that are still giving off radiation. Let me know if you have any more information on this topic.

Wednesday, August 29, 2007

World's Largest Diamond?
I just read that a company in South Africa is claiming to have found the largest diamond ever. It is said to be light green in color and about the size of a coconut! The weight is around 7000cts. Most experts who have seen the photo are skeptical of its authenticity. There is a picture here. Up to now, the largest diamond is the Cullinan Diamond. It weighed a measley 3106cts. in the rough.

Monday, April 02, 2007

Brilliance and Scintillation

Brilliance and scintillation are terms that are commonly used to describe a gemstone. Although they are related, they are not the same thing and there is often confusion over exactly what they mean. I hope here, to shed a little light on the issue (pun intended). They both describe how light interacts with a faceted gemstone.

Brilliance is sometimes referred to as “internal luster” or “liveliness”. It is the amount of light entering a stone that is returned to the eye of the viewer. It is in that brilliance that you see the color of the gem. The amount of brilliance is dependant on the type of stone, its clarity, and how it is cut. A stone that is not well cut and proportioned will “leak” light from the back of the stone. The result is dull or dark looking areas, called “areas of extinction”, when viewing the stone face up. With many commercially faceted gemstones, if you look down through the top of the stone, you can see through the bottom. This is called a window and is not ideal. In a well cut gemstone, the light passing through the top of the stone will not pass straight through but will be reflected back and the stone will be said to have more “brilliance”. If a stone is heavily included, the inclusions can diffuse or absorb some of the light entering the stone and reduce the brilliancy, making the stone appear fuzzy. Brilliance is sometimes described as a percentage, indicating the percentage of light entering the stone that is being reflected back.

Scintillation is sparkle. It’s the flashes you see as you move a stone in the light. It is determined by the optical properties of the particular gemstone and how it is faceted. The number of facets affects the amount of scintillation a stone shows. A gem cut with a smooth cone-shaped pavilion (the bottom part of the stone), could have high brilliance, but very little scintillation.

Another related term is “dispersion” or “fire”. It refers to the light being split into the spectral colors before it is reflected back to the eye. That’s the multi-colored flickering effect that diamonds are famous for. You also see it of course, in cubic zirconia and in a few colored gems.

You will see these terms used often in describing gemstones. Sometimes they are used correctly and sometimes not. As with most things there are disagreements over the exact definitions of the words. If you would like to share your understanding of these terms or add anything that will help clarify, please do.


Thursday, March 29, 2007

Just an update on the "Paraiba Chalcedony": I just saw some of the first runs of precision, machine cut Paraiba Calcedony. They were in small sizes like 2.5mm rounds and they were hot! In the smaller sizes they look much more transparent than the larger sizes, like the one in the picture below. They were bright and lively and the color was gorgeous. They really did look like little Paraiba tourmalines!

Sunday, March 04, 2007

Some of those Paraiba Chalcedony are up on my website now if you want to take a look. They are on this page:

Saturday, March 03, 2007

I've just gotten access to a good supply of a beautiful new gem material! It's being called Paraiba Chalcedony. These are faceted, translucent stones with a vivid blue color. The natural chalcedony is treated with a special process that infuses them with, among other things, copper. The result is a stable, permanent color throughout the gemstone (not just the surface). They are gorgeous! The color is much bolder and brighter than any blue chalcedony that you've seen before. I have them available in two different shades of blue, in a variety of sizes and shapes. I'll have them posted soon at www.palmbeachgems. com