BUYING

Grading words, explained

Teals lot descriptions use words from the gemstone trade to describe weight, shape, colour, clarity, treatment and origin. This page explains what those words mean in plain English. It does not replace the photographs, the individual lot's own description, or any report supplied with that lot. If a word in a lot's description is unclear, ask before you bid.

Weight and size

Carat (ct): The standard unit of weight used for gemstones. One carat equals 0.2 grams. Carat weight describes weight, not size: two stones of the same weight can look different sizes depending on their shape and how they are cut.
Carat weight: The row on a lot page that states the stone's weight in carats.
Measurements: The stone's own length, width and depth in millimetres. Reading the measurements lets you judge a stone's real size directly, rather than estimating it from the carat weight alone.

Shape and cut

Shape / cut: The row that names the stone's outline and style of faceting, for example Round, Oval, Cushion or Emerald cut. Here, "cut" mostly names a style, such as "round brilliant cut", rather than a quality grade.
Cut quality (cut grade): A separate rating of how well a stone's proportions and finishing were cut, most often seen for round brilliant diamonds, on a scale that includes grades such as Very Good and Excellent. This is different from shape, which only describes the outline.

Colour

Hue: Which colour the stone is, its base colour family, for example pink or blue.
Tone: How light or dark that colour is.
Saturation: How strong or pure the colour is.
Diamond colour grade: Diamonds are graded for colour on a lettered scale. D is the colourless end, and the scale moves through the alphabet toward more visible tint as the letters increase. Where the source record does not support one exact letter, a range is given instead, for example J/K/L.
Pink, Purple-Pink, Pinkish-Brown: For pink diamonds, these describe the one dominant colour of a single stone, given as alternatives. A listing that shows more than one of these words is describing different ways to describe that one colour, not claiming the stone shows several colours at once.

Clarity

Clarity: Whether a stone has visible internal features (inclusions) or surface marks (blemishes), and how visible they are.
Eye clean: No inclusions are visible to the unaided eye.
Included: Some inclusions are visible to the unaided eye.
Diamond clarity grade: Diamonds are graded for clarity on a lettered scale, from Flawless down through Included: FL, IF, VVS1, VVS2, VS1, VS2, SI1, SI2, I1, I2, I3. Where a lot's source record supports a specific grade, that grade is stated.
Clarity estimate: Included: For some pink diamonds, where the source record does not support a precise industry subgrade, the description gives Included as a visual estimate rather than a formally graded subgrade.

Treatment

Treatment: Something done to a stone, usually after it formed or was mined, to change or improve its colour or clarity.
Heat treated / heated: Colour or clarity has been changed using controlled heat.
Unheated: No heat treatment has been applied.
Untreated: No treatment of any kind is known to have been applied.
Irradiated: Colour has been changed using irradiation.
Fracture filled / glass filled: Cavities or internal fractures in the stone have been filled with a foreign substance, such as oil, resin or glass, to make them less visible. A lead-glass filled stone can be more fragile than an untreated one.
Oiled: Filled with oil, most often seen in emeralds, to make inclusions less visible.
Dyed, coated, bleached, waxed, impregnated: Other named ways a stone's colour or surface can have been treated.
None Identified: Teals has reviewed the record for this stone and found no identified treatment. This is a statement about our review, not a laboratory finding, and it is not the same as a report stating "untreated".

Natural and lab-grown

Provenance: The row that states whether the stone's material is Natural or Lab-grown. On an auction house's terms, "provenance" can also mean an item's history of previous ownership; on this row it means only the material's origin.
Natural: The stone formed in the earth. On Teals, "Natural" means earth-mined; it is not a statement about whether the stone has been treated. A natural stone can still have been treated after mining, so read the Treatments row separately.
Natural, earth-mined: The wording used for a natural diamond's material origin.
Lab-grown: The stone was grown in a laboratory rather than formed in the earth. Where identified, it is clearly labelled as lab-grown.
Doublet (assembled): A stone built from two joined pieces rather than cut from one solid piece, for example "Natural, earth-mined opal - assembled doublet".

Condition

Condition: Describes what is visibly there on the actual stone, for example a chip, or an internal feature reaching the surface, so you know what you are bidding on beyond the grading words above.

Reports

For a document from any other issuer, check with that issuer directly.

Report or document: A paper that describes one stone, identified by who issued it and its reference number. A GIA report comes from GIA, a gemological laboratory. An Argyle Pink Diamonds document comes from Argyle itself. Where a lot has one, the page names the issuer and the reference.
Report number: The reference number on a laboratory report. For a GIA report, the lot links to GIA's own Report Check so you can look the report up yourself.
Laser number: The number inscribed on the girdle of an Argyle pink diamond and printed on its Argyle document. The lot links to Argyle's own Diamond Check so you can look the number up yourself.

A note on what is not shown

Some grading words are deliberately left off the public specifications table under current catalogue policy: sapphire clarity grades and country of origin are not published on that table, even when Teals holds the information privately. Their absence is a publishing choice, not a claim that the answer is unfavourable.