Gem Treatment Methods

At EmeraldandGemstones we consider and buy gemstones that have been treated only by accepted and approved gemstone enhancement methods.  If a gemstone in our stock  is enhanced it has been done so according to accepted world wide gemological standards.

Code:  E    = Routinely Enhanced Gem
RE = Rarely Enhanced/No Known Enhancement 
NE = No Enhancement



Fracture Filling:  In gemstones where tiny surface reaching fractures and fissures are common, they can be filled to diminish their appearance and help strengthen the stone.  Emeralds are an example of such a stone.  Emeralds are most often treated with natural oils. If necessary, the stone can be re-oiled by the owner to keep up its appearance. This method of treatment, if done properly, does not diminish the value of the stone. Epoxy resins can also be used to fill fractures, however oiling Emeralds and other like gems is the preferred practice.

Heat:   One of the most common treatment practices is to heat gemstones to alter or enhance their color.  This is a permanent process.  Certain gemstones are routinely heat treated such as: Aquamarine, Topaz, Sapphire, Tanzanite, Green Tourmaline and Zircon.  This treatment does not in any way diminish the value of the gem.

Irradiation:  Radiation can be used to alter or enhance the color of a gemstone.  Since this process is permanent and the results are stable, it is a widely accepted practice.  Gems which can be irradiated include: colored Diamonds, Quartz, Tanzanite, Tourmaline, Kunzite, Yellow Beryl, and a few others.

Diffusion:  Diffusion treatment is most often done to colorless or very light Sapphires to turn them blue.  Chemicals are applied to the surface of the gem, which is then heated for a prolonged period of time.  The result is a permanent color, but only on the surface of the gemstone.  The center remains colorless, and the color can be scratched off.  This practice is relatively new and not widely accepted within the trade.

Dye:   Gems which have small surface cracks are sometimes filled with dye in the form of colored oil and epoxy.  Dye can be used on certain stones such as Emerald and Ruby to enhance color.  Some stones, such as Lapis and Chalcedony are naturally porous and absorb dye well.  In fact “Black Onyx” rarely occurs naturally, most times it is dyed Chalcedony.

Coating:  Some gemstones can be coated with wax or lacquer to enhance their smooth, flawless appearance.  Another method of coating a stone is with a foil backing.  Although it is relatively uncommon, gemstone settings can be lined with foil (sometimes colored) to add sparkle and alter or enhance color.  These practices are considered deceptive and the customer should be wary of them.

Why Emerald is So Special ?

For thousands of years Emeralds have been considered some of the most beautiful and valuable gems in existence. In many instances their value can exceed the value of a diamond of comparable carat weight. Emeralds are rare and precious gems of the beryl family, distinguished by their rich green color. The largest quantities of Emeralds are found in Brazil, Colombia and East Africa.

At our experienced gemologists carefully grade each Brazilian Emerald. Upon extraction from the mines in the state of Bahia, Brazil and the region of Minas Gerais, each gem is carefully cut, polished and calibrated. All stones arrive to our customers ready to be set in a piece of fine jewelry.

In addition to our high quality Brazilian Emeralds, we also offer other precious and semi-precious gemstones. These include Amethyst, Ametrine, Aquamarine, Citrine, Iolite, Peridot, Topaz, Tourmaline and more.

Emerald and Gemstones is a world-wide purveyor of the finest quality Brazilian Emeralds, precious and semi-precious gemstones. We offer only the highest quality merchandise. In business since 1981, our family owned and operated company began by offering gemstones from the mines of Bahia and Minas Gerais, Brazil, to the public at wholesale prices. We are committed to quality, excellence and customer satisfaction.

All of our gemstones are natural; none are synthetic.

In addition to the gem color grading information below, learn more about gem tone, clarity, treatment methods, cuts, and some gem conventions .

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Gemstone Color Grades

Emerald and Gemstones color scale is based upon our years of experience determining the intensity and purity of the primary color of a particular gemstone and therefore the desirability of the color within the gem.  For example, the greener the Emerald, the lower the number will be on the scale.  Emerald should have brilliant green as its primary color, so if it has around 85% and above primary color, it is graded  #1.  If it is 70-75% green, it is a #2, and so on.

We use this system, in conjunction with using words like “sky blue” to describe Aquamarine or “grass green” to describe Emerald or Peridot.  Although these words sound descriptive, everyone can have their own interpretation of what color “grass green” really is, so it is necessary to also use a more standard form of measure.

A more accurate way to describe color is to assess the hue (color classification i.e. red, blue green, etc., in reference to the spectrum), tone (lightness or darkness), and saturation (color purity). 


1 to 1.75 Outstanding Quality The very best and most sought after example of color in a gemstone.
2 to 2.75 Very High Quality Very high quality.  Precious and desirable.  In most cases you will see 60% to 75% primary color.
3 to 3.75 Very Good Quality This color is widely valued, but has a bit more secondary color.  You should see somewhere between 45% and 60% primary color. 
4 to 4.75 Good Quality This grade is good for setting in fine jewelry for your everyday collection.  You will see between 30% and 45% primary color. 
5 Low Gem Quality This grade is considered low gem quality. Examples of this color are more plentiful and considerably less in price. 

GIA-Type Color Scale

The charts below are based on the GIA (Gemological Institute of America) color stone grading system. The aspects of color with its three variables of tone, hue and saturation of a particular gemstone are listed. Normally you will see this system represented by a set of letters followed by numbers.Visible color and hues are represented by letters. The first number is the tone (lightness/darkness) of a gem. The second number is saturation of color in the particular gem. For example, when you see an Emerald assessed with the letter G indicating the color is green, primary with little or no secondary color or zoning. An assessed tone/saturation number of 7/6 making this jewel a green dark/strong or a G 7/6, is very high quality.




Red Red R
Red-Purple RP
strongly purplish Red stpR
slightly purplish Red slpR
orangy Red oR
Red-Orange RO


Orange Orange O
Orange-Red OR
reddish Orange rO
Red-Orange RO


Yellow Yellow Y
orangy Yellow oY
greenish Yellow gY
Yellow-Green YG


Green Green-Yellow GY
strongly yellowish Green styG
yellowish Green yG
slightly yellowish Green slyG
Green G
very slightly bluish Green vslbG
very strongly bluish Green vstbG
Green-Blue GB


Blue Blue-Green BG
very strongly greenish Blue vstgB
greenish Blue gB
very slightly greenish Blue vslgB
Blue B
grayish Blue gyB
Blue-Violet BV


Violet Violet-Blue VB
bluish Violet bV
Violet V
bluish Purple bP
Purple P
reddish Purple rP
Purple Red PR