Gem & Jewelry Pocket Guide
Gem & Jewelry Pocket Guide
1/Colored Stone Price Factors in a Nutshell
The following factors can affect the prices of colored gems:
Cut quality (proportions and finish)
Stone shape and cutting style
Carat weight or stone size
Clarity (degree to which a stone is free from flaws)
Transparency (degree to which a stone is clear, hazy, cloudy or opaque)
Treatment status (untreated or treated? type and extent of the treatment)
Distinctness of phenomena if present (e.g., stars, cat's-eyes, alexandrite's color change, opal's play-of-color)
The pricing of colored gems is also determined by market factors such as demand, form of payment, buyer's credit rating, amount purchased and competitors' prices. Sometimes you can find the same dealer selling a stone of higher quality for less than one of lower quality. This is because the rough for the higher quality stone may have cost less. Or, the rate of currency exchange could have been more favorable at the time the dealer purchased it. Therefore, you should not assume that higher price necessarily means higher quality. Conversely, lower price is not necessarily indicative of a deal.
Why the 4 C's isn't an Adequate Pricing System
You may be surprised that there are more than four price factors if you've heard about the 4 C's of color, cut, clarity and carat weight. The 4 C's system of valuing gems is a clever, convenient way to explain gem pricing. The problem is that it causes consumers to overlook the importance of cut quality, transparency and treatment status.
If you see a mini gem-lab report stating that the shape/cut of a gemstone is round brilliant, you may assume that this tells you everything about the cut of stone when in fact it doesn't. The quality of the cut is important and it's a separate price factor from shape and cutting style.
If you're not informed about gem treatments, you may assume, for example, that two equally attractive jade stones should be priced alike. However, if one is dyed or bleached and the other is of natural color, their prices should be quite different. Chapter 2 describes the ways in which gems are treated.
If you're comparing a cloudy stone to a transparent one, be aware that transparency can have a significant impact on each stone's value. Transparency and clarity are often interconnected, but they're not the same. A stone can be transparent like crystal yet have a low clarity. Likewise a stone may be flawless, yet be cloudy and milky in appearance.
Price Factors Explained
COLOR: It can be broken into three components:
Hue: Basic spectral colors like those in a rainbow such as blue, green and bluish green. Brown, black, gray and white aren't hues because they're not part of the color spectrum.
Tone: Amount of color, the degree of lightness or darkness
Saturation : Amount of grey or brown masking the hue. This component is also called "intensity" and "chroma" depending upon the color system you're using. Stones with a high color saturation have hardly any grey or brown masking the hue.
Gem dealers often disagree on what is the best hue and tone for a given gemstone such as sapphire or emerald. They agree, however, that for most gem varieties, the less brown or gray that is present, the more valuable the stone. For example, the center ruby in figure 1.1 is worth much more than the brownish rubies on each side.
If you're buying a gemstone for yourself, it doesn't matter what color you choose as long as you like it and the color looks good on you. However, when buying gems for resale or as gifts, find out what hues and tones gem dealers prefer. Chapter Four describes the preferred colors for various gem varieties. Usually the strongest and richest colors are the most valuable. Very light and