When buying cultured pearls, consumers must consider several quality characteristics that are very different from the four C's of diamonds or gemstones. Nacre quality is very important. The nacre is the layers of protective coating - a pearly substance - that grows around a pearl nucleus. Experts warn that only pearls with a sufficient layer of nacre will last through years of wear; thin-nacre pearls often peel or crack. A nacre that is less than 0.35 mm is considered too thin, and thicker is always better.... (2004) Complete Story
For the past 125 years, textbooks and museum displays have relied on the beauty of tiger's eye to add interest to an often dry description of pseudomorphism, a term that simply means the replacement of one mineral by another while preserving the form of the original mineral. Mineralogists once thought that the stunning play of light emerging from tiger's eye resulted from the infiltration and dissolution of the fibrous mineral crocidolite, a deep blue, asbestos like silicate, by hot waters rich in dissolved silica. Tigerís eye was viewed as a spectacular form of chalcedony and is often included as a variety of quartz in mineral guides.... (2003) Complete Story
An experienced bench jeweler will often be able to create almost any design that doesn't actually violate the laws of physics. But colored stones are softer and typically less durable than diamonds, and a setting designed for a diamond may spell disaster with an opal or an emerald. The resulting creation may be beautiful when you first present it to the customer, but if the piece is worn frequently, it's likely to make a quick return to the jeweler's bench for repair. In this article expert gem setters share their tips and warnings for working with colored stones.... (2004) Complete Story
Beryllium diffusion typically brightens the color of ruby or sapphire, making a stone more yellow, orange, or red, depending on the original color. Because the color change can go all the way through the stone, the treatment is more difficult to identify than traditional diffusion, which is an easily-detected surface treatment. When beryllium diffusion was first introduced to the market in 2001, uncertainty about disclosure created a controversy that led to a sharp drop in prices for the diffused stones. Today, beryllium-diffused corundum sells for a fraction of the price of its natural or heated counterparts....
(2006) Complete Story
Well worth a fresh inspection under the loupe is some fine blue spinel currently on the market. An ancient group of related minerals, spinel likely owes its name to the Old Latin sintill -- from which the word scintillation was derived. And a good descriptive name it is. If you havent considered blue spinel for a fine jewelry piece, remember that its density assures a high polish when faceted. Rating an 8 on the Mohs scale, this gem doesnt need to be coddled in protective mountings, either.... (2006) Complete Story