One of the most sought-after and hard-earned talents that one seeks from a rough gem buyer is the ability to predict the eventual appearance of the as-yet non-existent cut and polished end product. Sometimes the rough mineral looks unattractive to the untrained eye, but the experienced rough buyer sees its real potential.

We took a photo of a tanzanite gem to capture its merged green/blue color and analyzed it to define its overall color, as seen by the human eye.

Commercial names, or trade names, are commonly used by merchants and buyers, and usually symbolize top quality, rare shades of gems. Their main purpose is to elevate the stature of certain gems above others of the same variety that show less attractive shades. Commercial names are becoming increasingly popular, fueled by buyers and laboratories alike. One issue, however, seems to continuously pop up - the color definition borders of each name.

Color is a challenging issue, to say the least. Think of the dilemmas one faces when describing, matching, communicating and grading color in gems, even in colored diamonds. I mean, how many times have you tried to assemble a pair of fancy colored diamonds for earrings, just to discover that your two fancy yellow candidates are not even close to be defined as a "matching pair"? In this Part II article, we continue our color journey into the challenges posed in color grading of colored diamonds and present our innovative solutions.

Gray is one of the less attractive colors among fancy diamonds. Even when it appears in conjunction with other popular colors, such as blue or green, its effect on the overall price is negative, regardless of its dominance within the stone. But what is the current extent of this effect? We thus set out to explore this issue.

In reality, some colored stones are very difficult to describe. Some gems produce peculiar colors, which can be very confusing, even for the most experienced expert ‒ for example, various gems may display a uniform color that lies in the border between two hues, others may possess an optical phenomenon that causes the gem to display many different colors, just to name two possible cases.

In the past few years, a peculiar trend seems to have been taking place in the gem trade. In gem shows and the jewelry market, gems seem to be losing their colors! Somehow paler shades of any color seem to be doing better and better each year, to the point that even gems with only the slightest hint of color appear to be in high demand.

Since the dawn of history, men and women have realized that in order to expose the beauty of gems, it is essential to cut and polish them. Though some gem crystals look great in their natural form, cutting and polishing bring out the best in them, facilitating their setting in jewelry. But, it is really not that simple!

It is always a thrill to go on a gem buying spree, isn’t it? It is especially so, when one travels to the source in search of newly unearthed wonders. A few weeks ago, my son Kobi and I did just that. We traveled to Arusha, Tanzania, to attend the Arusha International Gem, Jewelry & Minerals Fair in the charming Mount Meru Hotel. I still recall the first time I stepped foot in Africa way back in the mid seventies. And here I am, four decades plus later, in this amazing age of technology. The Arusha fair exemplifies how far we have all come.

An unusually large 9.13-ct. emerald-cut Santa Maria Africana-colored aquamarine gemstone was loaned to Gemewizard® for color analysis.

Gem shows are quite an experience for gem lovers like us. Personally, I have never discovered the secret of how to differentiate and spot a serious buyer from the crowds of visitors. But I want to tell you of the first and only time in history that I was bewildered by a dog!

Anyone who has traveled to Thailand has likely to have been confronted by this famous, but initially confusing sales pitch: "Same, same but different." In other words, this is exactly the same as what you asked for BUT with a different color or pattern. You get it? Okay, you surely are asking yourself, what has all this got to do with gems?

Blue diamonds were the highlights of last year’s auction scene, with some exceptional gems, among them, The Oppenheimer Blue, The Cullinan Dream and The De Beers Millennium Jewel 4 to name a few. Therefore, this seemed like a great opportunity to share with you how the borders between the fancy grades for blue colored diamonds are determined.

In this article, we look at the relationship between the various fancy color diamonond's color grades in terms of price. We present the relative price variations between the main fancy color grades of a 1.00-carat pure yellow colored diamond (without secondary moderators) as they currently appear in our extensive database of about $350 million worth of GIA-certified fancy colored diamonds currently being offered for sale on the Internet by leading traders.

Ametrine is a bi-colored variety of quartz, composed of amethyst, with purple hues, and citrine, with yellow to orange hues. Almost all polished ametrine gems are fashioned in an emerald-cut style to emphasize the color border. We had the oppotunity to analyze some remarkable ametrine images received courtesy of L. Allen Brown, the owner of All That Glitters from Methuen, MA.

The Morogoro area in Tanzania is the source of many gemstones, and most notably spinel, ruby, sapphire and tourmaline. For many years fine quality chrome tourmaline were mined in this and other areas in Tanzania, and during past decade substantial quantities have been produced of fine quality rough tourmaline in earth tone colors, ranging from reddish orange to brown to yellow and green. These highly dichroic gems, show different colors and/or different intensities when observed from different angles, and they were the subject of our color analysis and research.

Would you believe me if I told you that the time of day that you close a deal may well affect your success in the gemstone business? It's true, and it is something I learned relatively late in life. In fact it took me more than 30 years before realizing why dealers in Bangkok insisted on showing me the sapphire lots before lunch and the ruby lots only in the afternoon.

"A gem, in order to be a gem and valuable, has to have beauty, rarity and durability." It was the first sentence uttered by my teacher, Michael O'Donoghue, when I began my formal gemological studies. Which brings me to the subject of spinel. I don't know why, but in the early days, like most gem dealers I never thought much of them. But over more than a decade, and especially after several close encounters with spinels in Mahenge, Tanzania, I have become totally enchanted by the gemstone.

Amber is not exactly a gemstone. It is a gem material derived from the petrified resin of ancient 'Umbrella Pine' trees, as well as other species. From a color perspective it is located in the white to yellow to orange-red range, although greens (enhancements) and rare blues (high blue fluorescence) can also be found. Among its many sources, the Baltic Sea region is considered to be one of the more prestigious. In this color analysis article we explore the range of colors of natural Baltic Sea ambers.

Zultanite, also known as Csarite®, is a rare color-change variety of diaspore found exclusively in Turkey. It is named for the sultan rulers who used to govern the region in the Anatolian mountains where it is sourced. When holding a zultanite gemstone in your hand, you will find it hard to describe its body color. The variety of colors produced by the gem and the distinct differences between them make it impossible for a single color description. But the GemePro™ analysis provided us with a practical solution.