Tolerance Ranges for Jewelry Authenticity Guarantee

Authenticity Guarantee for jewelry is limited to a review of claims regarding item quality and characteristics listed by the seller. These claims are assessed within defined ranges and tolerances. Below is a detailed overview of those defined ranges and tolerances.

Diamond clarity

Clarity is evaluated based on the area of the stone that is visible. Areas of the stone that are covered by the setting will not be part of the evaluation. Stones listed as VVSI, VVS2, VS1, VS2, SI1, SI2, I1, I2, I3 will be verified with a - 1 tolerance.

Clarity grade for Flawless or Internally Flawless stones will not be confirmed. Stones having a carat weight of less than 0.15ct will also not be verified for diamond clarity.

Diamond color

For colorless diamonds, jewelry experts will verify the listed color value and accept a –2 tolerance from the lowest value indicated. For example, if a listing states the color is G and the expert determines the color is likely I, the diamond will pass color verification. Similarly, if the listing states the color is J-K and is likely L-M, the diamond will pass color verification.

Please note, D-Z diamonds with a weight below 0.15ct will not be verified for color.

For fancy-colored diamonds, experts will only confirm non-trade term hues. For example, if listing states that a diamond is “fancy yellow”, experts will confirm that the hue is yellow, but they will not confirm the saturation level. If the listing states that a diamond is “Canary yellow”, experts will confirm that the hue is yellow, but will disregard the term “Canary”.

Colored stones color

If a gemological or trade term is used in the listing and the color appears to be close to term definition, it is acceptable. If a non-gemological term is used in the listing, verification will confirm the term used represents the color of the actual item.

A gemological or trade term describes specific colors and qualities of gemstones that are typically assigned to gemstones of superior quality and rarity. Common trade terms for colored gemstones include Pigeon Blood Red, Royal Blue and Padparadscha Sapphire. These terms must fulfill the Gübelin Gem Lab criteria for proper use which requires the gemstone accurately represent the trade term and its corresponding Gübelin Gem Lab definition.

Carat weight

Stones weighing 0.40 ct. or more per stone have an acceptable tolerance of -10%. Stones that weigh less than 0.40 ct. have an aggregate tolerance of -25%.

Assembled stones

Assembled stones are stones constructed out of two or more materials and are not eligible for Jewelry Authenticity Guarantee.

Common assembled stone types include:

  • Doublet: A doublet consists of two joined segments
  • Triplet: A triplet has three segments, or two segments separated by a layer of colored cement

Item size

An expert will verify that the size of the item matches the size listed by the seller (i.e., inches, millimeters, standard ring sizes, etc.). Necklaces, bracelets and bangles will have a tolerance of +/- ¼ the unit of measurement. Rings will have a tolerance of +/- 1. For long necklaces, a tolerance of up to +/- ½ will be accepted.

Please note, resizing an item may result in metal purity and/or composition variances in the area that was modified for resizing purposes (i.e., metal alloys used to modify size may affect metal purity in sections modified).

Gemstone treatments

Gemstones that are eligible for Authenticity Guarantee are commonly treated. Below is a list of the most common gemstone treatments that are acceptable for verification. This list does not represent all possible treatments that could apply.

  • Ruby: Heating, healing of fractures (residues), clarity enhancement, glass filling, dyeing
  • Sapphire: Heating, clarity enhancements, titanium diffusion, beryllium diffusion, dyeing
  • Emerald: Clarity enhancement, dyeing
  • Tourmaline: Heating, clarity enhancement, irradiation (red or pink)
  • Topaz: Heating (pink), irradiation (blue, brown), coating
  • Tanzanite: Heating, clarity enhancement
  • Peridot: None
  • Garnet: Heating (demantoid)
  • Aquamarine: Heating
  • Cat’s eye chrysoberyl: None
  • Alexandrite: Clarity enhancement
  • Spinel: Heating
  • Morganite: Irradiation

Please note, clarity enhancements can be performed on any stone that has a fracture but is more common in some gemstones than others.

Treatments that cannot be verified

  • Heating: Aquamarine, demantoid garnet, topaz (pink), tourmaline (blue to green), tanzanite. Low temperature in ruby and sapphire is sometimes detectable but not under Authenticity Guarantee.
  • Irradiation: Cannot be proven in any colored stone. Some blue topaz is assumed to be treated because of its depth of color.
  • Beryllium diffusion: Can be detected but only with sophisticated chemical analysis.

Additionally, claims that colored stones are untreated will not be verified.

Gemstone treatment definitions

  • Heating: Heating a stone at temperatures that may vary from 300C to 1800C (depending on the stone) to change the color or improve clarity.
  • Healing of fractures: Causing fractures to grow back together during heat treatment using a flux. This is almost exclusively done to rubies and is called ‘residues’ in the gemstone trade because of the whitish flux that is left behind.
  • Clarity enhancement (fracture filling): Filling fractures that are open to the surface with substances such as oils, resins or glass to make them less visible. In most cases this is not a permanent treatment.
  • Glass filling: Usually refers to rubies filled with lead glass, although it can apply to silica glass. Lead glass filling is mostly used on very low-quality ruby that could not be cut into a stone if it were not held together by the glass.
  • Titanium diffusion: Using high temperature heat treatment to cause titanium to enter the surface of a sapphire, creating a blue color in a surface layer.
  • Beryllium diffusion: Using high temperature heat treatment to cause beryllium to enter the surface of a ruby or sapphire to change the color, depending on the starting material. This treatment can be in a surface layer or extend throughout the stone. It is not common for rubies.
  • Irradiation: Exposing a stone to ionizing radiation such as fast electrons or gamma rays to change its color.
  • Coating: Applying a foreign material to the outside of a gemstone to change its color. This treatment is usually not permanent.
  • Dyeing: Filling fractures or openings at the surface of a stone with a foreign colored material to create an artificial color.

Undetermined results

In some cases, if it’s not possible to determine whether an item is unstable, laboratory-grown or has been treated using then-current techniques and technology, treatment status of the item is undetermined and will pass this verification step. 

Stone count

If an item has numerous stones that weigh less than 0.20 ct., the precise number of stones in the item will not be verified.

Metal gram weight

If listed, the total gram weight of the metal-only items will be verified. Metal weights will not be verified on finished jewelry items containing other non-metal materials (i.e., stones, enamel, etc.).

For metal only items, gram weight has a tolerance of minus 5%.

Metal purity

The following metals and metal purities are eligible for verification.

Please note, resizing an item may result in undisclosed composition variances (i.e., metal alloys used to modify size may affect metal purity).

Silver purity conversion chart

Silver = Ster., Solid Silver or Sterling Silver with at least 92.5% purity Purity less than 92.5% silver cannot be marked as Ster., Solid Silver and/or Sterling Silver unless the item is a coin or coin silver having a minimum purity of 90% or more.

The term "silver" can be used to describe a product or part composed throughout of an alloy containing less than 900 parts per thousand, if the term is accompanied by an equally conspicuous, accurate designation of the item’s silver content.

Common name Tolerance Parts of silver % Of silver purity Fineness
 70% Silver <90% 700/1000 70% 700
 80% Silver <90% 800/1000 80% 800
Coin 90-92.49% 900/1000 90% 900
Sterling Silver 92.50-95.79% Ster 925/1000 92.50% 925
Brittania 95.80-99.89% Ster 958/1000 95.80% 958
Fine or Pure Silver 99.90-100% Ster 999.9/100 99.90% 999

Gold purity conversion chart

Gold = k, Kt, Karat, K Gold, Kt Gold, Karat Gold, Gold with at least 99.9% purity

Please note, purity range below 9K will not be verified

Number of karats Tolerance Parts of gold % Of gold purity Fineness
8k <10K 8/24 33.3 333
9k, 9Kt, 9 Karat, 9K Gold, 9Kt Gold, 9 Karat Gold <9.49k 9/24 37.5 375
10k, 10Kt, 10 Karat, 10K Gold, 10Kt Gold, 10 Karat Gold 9.5-10.49k 10/24 41.7 416/417
11k, 11Kt, 11 Karat, 11K Gold, 11Kt Gold, 11 Karat Gold 10.5-11.49k 11/24 45.8 458
12k, 12Kt, 12 Karat, 12K Gold, 12Kt Gold, 12 Karat Gold 11.5-12.49k 12/24 50 500
13k, 13Kt, 13 Karat, 13K Gold, 13Kt Gold, 13 Karat Gold 12.5-13.49k 13/24 54.1 541
14k, 14Kt, 14 Karat, 14K Gold, 14Kt Gold, 14 Karat Gold 13.5 - 14.49k 14/24 58.3 583/585
15k, 15Kt, 15 Karat, 15K Gold, 15Kt Gold, 15 Karat Gold 14.5-15.49k 15/24 62.5 625
16k, 16Kt, 16 Karat, 16K Gold, 16Kt Gold, 16 Karat Gold 15.5-16.49k 16/24 66.6 666
17k, 17Kt, 17 Karat, 17K Gold, 17Kt Gold, 17 Karat Gold 16.5-17.49K 17/24 70.8 708
18k, 18Kt, 18 Karat, 18K Gold, 18Kt Gold, 18 Karat Gold 17.5-18.49k 18/24 75 750
19k, 19Kt, 19 Karat, 19K Gold, 19Kt Gold, 19 Karat Gold 18.5-19.49k 19/24 79.1 791
20k, 20Kt, 20 Karat, 20K Gold, 20Kt Gold, 20 Karat Gold 19.5-20.49k 20/24 83.3 833
21k, 21Kt, 21 Karat, 21K Gold, 21Kt Gold, 21 Karat Gold 20.5- 21.49k 21/24 87.5 875
22k, 22Kt, 22 Karat, 22K Gold, 22Kt Gold, 22 Karat Gold 21.5-22.49k 22/24 91.7 916/917
23k, 23Kt, 23 Karat, 23K Gold, 23Kt Gold, 23 Karat Gold 22.5-23.49k 23/24 95.8 958
24k, 24Kt, 24 Karat, 24K Gold, 24Kt Gold, 24 Karat Gold, Gold 23.5-24.5k 24/24 99.9 999

Palladium purity conversion chart

Palladium = Pall., Pd. or Palladium if preceded by a number indicating parts per thousand of pure Platinum

Marking Tolerance Parts of palladium % Of palladium purity Fineness
500Pd., 500Pall. 495-990Pt., 49.5-99% 500/1000 50% 500
950Pd., 950Pall. 940-999Pt., 95-99% 950/1000 95% 950
999Pd., 999Pall. 990-1000Pt., 99-100% 999.9/1000 99.9% 999