Gemstones Buying Guide Series No. 4

Gemstones Buying Guide Series No.4

Published only on Monday’s.  Extracted from Gemstone Buying Guide by Renee Newman GG

 

Colored Gem Price Factors :

Following factors can affect the prices of coloured gemstones:

-          Color

-          Clarity

-          Transparency

-          Shape

-          Cutting Style

-          Cut Quality

-          Carat Weight or stone size

-          Treatment status

-          Place of Origin

-          Distinctness of phenomena

 

Carat Weight or stone size is also an important value factor.  In most cases, the higher the carat weight category, the greater the per carat price of a gem.  A carat is a unit of weight equalling 1/5 of a gram.

Many translucent to opaque stones such as jade, malachite and chalcedony are sold by the piece of or stone size, not by weight.  Designer cuts may also be priced per piece, and coloured stones under approximately half a carat are often priced according to millimetre size.

 

Treatment status includes 3 elements which can be important if you are spending a substantial amount of money on a gemstone:

1.       Is the stone treated or untreated?  Has the stone undergone a process other than cleaning cutting or polishing to improve its natural appearance? Most colored stones are treated in some way by man.  High quality untreated gems are usually the most highly valued because they are more rare and they are natural.  However ugly untreated stone is typically worth less and harder to sell then one that is attractive and treated.  That is why gems are treated.

2.       What treatment(s) did the stone undergo?  Not all treatments are equal.  Some treatments, such as dyeing and cavity filling, have more negative impact on value than others, like heat treatment, which is well accepted.  Therefore it pays to find out what gem treatments were used on a gem before assessing its value.

3.       What is the extent of treatment?  This applies to clarity enhancements such as fracture filling.  For example, practically all emeralds have tiny fractures.  So it is customary to fill these fractures with oil, wax or epoxy-type substance to mask them and sometimes increase durability.  Assume that all emeralds you see for sale have been clarity enhanced, unless otherwise stated.  Naturally a stone with a minor amount of filling is more valued than one with a substantial amount throughout the stone.  Therefore gem labs now indicate on their documents the extent of the filling process, often by describing it as minor, moderate, significant or none.