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Gemstone Enhancements
The term enhancement is defined as any treatment or process other than cutting and polishing that improves the appearance (color/clarity/phenomena), durability, value or availability of a gemstone. In today’s gem marketplace, many gemstones have been enhanced by a variety of methods. Such processes may range from simple heating (such as with tanzanite) to high-tech irradiation (such as blue topaz).
At the Collector, we take enhancement disclosure seriously and guarantee, to the best of our abilities, to provide our customers with complete information on any and all enhancements to which a gem has been subjected. While many enhancements are currently undetectable, we do our best to provide all the information you need for informed buying decisions.
The guidelines we follow are those of the AGTA and are the most stringent in the industry. In addition, we have modified these guidelines slightly in areas where we feel they are not stringent enough (example: flux healing of ruby).
Some gemstone enhancements are less stable than others, meaning that the appearance of a gem may change with time. It is the general policy of the Collector to sell only those gemstones whose enhancements (if any) have good to excellent stability. In the event that we offer a gem with less than good stability, we will ensure you are aware of the special care needed for that stone. A gemstone enhancement is considered stable as long as the gem does not change in appearance (color and/or clarity) under normal wear, cutting, cleaning, repair or display conditions. Gemstones can be divided into three basic enhancement categories.
  • Not Enhanced (N)
    The “N” symbol is used on our invoices to indicate one of two situations. First, there are certain gemstones that are not currently known to be enhanced (alexandrite, some garnets, etc.). Second, the “N” symbol may also be used for a gem where it can be proved via gemological or other means that a gem has not been subjected to any enhancement. When you see the “N” symbol on our invoice, we guarantee that the gem in question is unenhanced.

  • Normally Enhanced (E)
    The “E” symbol is used for gemstones that are routinely enhanced. Since many enhancements are difficult or impractical to prove definitively, unless otherwise indicated, our approach is to assume that such enhancements have been applied to that particular gemstone. This assumption is made to protect both buyer and seller. If a more specific method of enhancement is known, then the specific enhancement code will be used.

  • Nontraditional Enhancements (T)
    For gemstones not covered by the “N” and “E” symbols, a code covering the specific gemstone enhancement will be listed.

Symbols For Specific Forms of Enhancement

  • B = Bleaching: The use of heat, light and/or chemicals or other agents to lighten or remove a gemstone's color. This is often accompanied by subsequent dying and/or impregnation. Example: bleached cultured pearl; bleached/impregnated jadeite (‘B-jade’)
  • C = Coating: The use of such surface enhancements as lacquering, enameling, inking, foiling, or sputtering of films to improve appearance, provide color or add other special effects. Example: coated diamond
  • D = Dyeing (staining): The introduction of coloring matter into a gemstone to give it new color, intensify existing color or improve color uniformity. Example: dyed green jadeite
  • F = Filling: The filling of surface-breaking cavities or fissures with colorless glass, plastic, or some similar substance. This process will improve durability, appearance and/or add weight. Example: ruby
  • Fh = Flux healing: During heat enhancement, fluxes (or heat alone) may be used to heal fractures/fissures which were formerly open. The process dissolves the walls of the fractures and redeposits the molten gem material, healing the fractures closed. Example: ruby (particularly that from Möng Hsu, Burma)
  • H = Heating: The use of heat to alter color, clarity, and/or phenomena. Example: Ruby, sapphire, tanzanite, aquamarine, demantoid garnet
  • I = Impregnation: The impregnation of a porous gemstone with a colorless agent (usually plastic) to give it durability and improve appearance. Example: Stabilized turquoise
  • L = Lasering: The use of a laser and chemicals to reach and alter inclusions. Example: diamond
  • O = Oiling/Resin Infusion: The filling of surface-breaking fissures with a colorless oil, wax, resin or other colorless substances, except glass or plastic, to improve the gemstone’s appearance. Example: emerald
  • R = Irradiation: The use of neutrons, gamma, ultraviolet and/or electron bombardment to alter a gemstone’s color. The irradiation may be followed by a heating process Example: blue topaz
  • U = Lattice (‘bulk’ or ‘surface’) Diffusion: Outside-in diffusion of coloring chemicals via high-temperature heat treatment to produce color and/or asterism. Example: lattice diffusion-treated sapphire
  • W = Waxing/Oiling: The impregnation of a colorless wax, paraffin and/or oil in porous gemstones to improve appearance. Example: jadeite
Natural Gemstone Enhancement Chart
(based on the AGTA Source Directory 2000–2001)
Natural
Gemstone
Enhancement
Symbol
Description
Used
Frequency
Encountered
Stability Care
Requirements
Agate
D
Usually
Excellent to good
Normal

     Fire Agate

N
Normal
Alexandrite
N
Normal
Amber
E or H
Usually
Very good to good
*Special
 
D
Rarely
Variable
Special
Amethyst
E or H
Occasionally
Excellent
*Special
Ametrine
N
Normal
Andalusite
N
Normal
Aquamarine
E or H
Usually
Excellent
Normal
Beryl
R
Maxixe
Always
Poor
X-Special
 
R
Yellow
Usually
Variable
Special
 
N
Yellow-green
Normal
 
E or O
Red
Commonly
Very good to fair
Special
Chalcedony
D
Black
Always
Excellent to good
Normal
 
D
Banded
Usually
Excellent
Normal
 
D
Green
Usually
Good to fair
Special
 
D
Blue
Commonly
Good to fair
Special
 
E or H
Carnelian
Usually
Excellent
Normal
 
D
Carnelian
Occasionally
Excellent to good
*Special 
 
D
Jasper
Occasionally
Excellent
Normal
 
N
Chrysoprase
Normal
Chrysoberyl
N
Transparent
Normal
 
R
Cat’s eye
Occasionally
Excellent
Normal
Citrine
E or H
Usually
Excellent
Normal
Coral
N
Black
*Special 
 
E or B
White
Commonly
Good
Special
 
E or W
Pink
Commonly
Good
Special
 
I
Orange
Commonly
Good
Special
 
B
Gold
Usually
Very good
Special
 
D
Red
Occasionally
Variable
X-Special
Natural
Gemstone
Enhancement
Symbol
Description
Used
Frequency
Encountered
Stability Care
Requirements
Diamond
L
Occasionally
Very good
Normal
 
C
Rarely
Very good to poor
Special
 
F
Occasionally
Very good
Special
 
HP
Rarely
Unknown
Special
Diamond – Fancy
R
Occasionally
Excellent to very good
Special
 
L
Occasionally
Very good
Normal
 
F
Rarely
Very good
Special
 
C
Rarely
Fair to poor
Normal
 
H
Rarely
Unknown
Normal
Diopside – Chrome
N
*Special 
Emerald
E or O
Usually
Very good to fair
Special
 
D
Occasionally
Variable
Special
Garnet
N
All varieties
*Special
 
E or H
Some demantoid
Commonly
Very good
*Special
Hematite
N
Normal
Iolite
N
Normal
Jade – Jadeite
E or W
Commonly
Fair
Special
 
B and I
Green/purple/white
Commonly
Very good to good
Special
 
D
Occasionally
Variable
Special
 
B and W
Rarely
Poor
Special
Jade – Nephrite
D
Rarely
Unknown
Special
Kunzite
E or H
Commonly
Fair
Special
 
R
Commonly
Fair
Special
Natural
Gemstone
Enhancement
Symbol
Description
Used
Frequency
Encountered
Stability Care
Requirements
Lapis lazuli
E or W
Commonly
Fair
Special
 
D
Commonly
Variable
Special
Moonstone
N
Normal
Morganite
E or H
Commonly
Excellent
Normal
Opal
O
White/black
Rarely
Fair
Special
 
I
Rarely
Good
Special
 
O
Boulder
Usually
Good
Special
 
D
Matrix
Commonly
Good
Special
 
N
Fire opal
*Special
 
I
Cat’s eye
Usually
Good
Special
 
I/O/D
Hydrophane
Commonly
Good to fair
Special
Pearl – Natural
E or B
White
Usually
Very good
Special
 
D
Rarely
Very good to good
Special
Pearl – Cultured
E or B
White
Usually
Excellent
Special
 
D
Many colors
Usually
Variable
Special
 
R
Black/gray
Occasionally
Very good
Special
Peridot
E or O
Rarely
Good to fair
Special
 
F
Rarely
Good
Special
Ruby
E or H
Usually
Excellent
Normal
 
Fh
Commonly
Excellent
Normal
 
O
Occasionally
Good to fair
Special
 
D
Rarely
Poor
Special
 
R
Rarely
Unknown
Normal
 
F
Commonly
Very good to fair
Special
 
U
Rarely
Good
Special
Natural
Gemstone
Enhancement
Symbol
Description
Used
Frequency
Encountered
Stability Care
Requirements
Sapphire
E or H
Usually
Excellent
Normal
 
U
Occasionally
Good to fair
Special
 
O
Occasionally
Good to fair
Special
Sapphire – Fancy
E or H
Usually
Excellent
Normal
 
R
Yellow/orange
Occasionally
Very poor
X-Special
 
O
Occasionally
Good to fair
Special
 
U
Occasionally
Good to fair
Special
Serpentine
D
Various colors
Commonly
Good to fair
Special
 
E or W
Commonly
Very good to good
Special
Spinel
N
Normal
 
O
Occasionally
Good to fair
Special
Sugelite
N
Normal
Sunstone
N
Normal
Tanzanite
E or H
Usually
Excellent
*Special
Topaz
R
Blue
Usually
Excellent
Normal
 
R
Yellow/orange
Occasionally
Variable
Special
 
R
Green
Occasionally
Poor
X-Special
 
U
Green
Usually
Good
Special
 
N
Brown
*Special
 
E or H
Red/pink
Usually
Excellent
Normal
Natural
Gemstone
Enhancement
Symbol
Description
Used
Frequency
Encountered
Stability Care
Requirements
Tourmaline
N
Chrome green
Normal
 
N
Cat’s Eye
Normal
 
E or H
Yellow/orange
Rarely
Excellent
Normal
 
R
Yellow/orange
Rarely
Very good
Normal
 
E or H
Green/blue
Commonly
Excellent
Normal
 
O
Any color
Occasionally
Good to fair
Special
 
E or H
Pink/red/purple
Occasionally
Excellent
Normal
 
R
Pink/red/purple
Commonly
Good
Normal
 
D
Pink/red/purple
Occasionally
Fair to poor
Special
Turquoise
W
Commonly
Fair to poor
Special
 
D
Rarely
Poor
X-Special
 
I
Commonly
Good
Special
Zircon
N
Green/brown
*Special
 
E or H
Blue/colorless
Always
Fair to poor
Special
 
E or H
Yellow
Rarely
Good
Special
 
E or H
Red
Commonly
Fair to poor
Special

Notes:

  • The “N” symbol is used only for gemstones which we guarantee have not been enhanced.
  • All jewelry (with or without stones) requires special care; some jewelry requires extra-special
    (X-Special) care.
  • * Indicates a gemstone which generally requires special or extra-special care (although the need for care is not necessarily related to the enhancement).

If you need additional information on gemstone enhancements or care, call us at: 800-854-1598.

 

The Collector Fine Jewelry

The Collector – Fallbrook
912 So. Live Oak Park Rd., Fallbrook, CA 92028
Tel: 800-854-1598; 760-728-9121
Fax: 760-728-9121

Hours:
10:00 a.m. to 5:00 p.m. Monday–Saturday
The Collector – Four Seasons Resort
7100 Four Seasons Point, Carlsbad, CA 92011
Tel: 760-603-9601

Hours:
10:00 a.m. to 6:00 p.m. daily

E-Mail: info@collectorfinejewelry.com

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