Glossary for Gemstones 101
The vocabulary used to describe gems, particularly mined versus other gems, is not set in stone (I know – groan!). Below is an alphabetical list and layperson’s definition of some of the most common terms.
Come back as the list is updated.
Carat – the size of precious gemstones; applies to mined, synthetic and simulant gems. Simulants are often sized in mm instead.
Clarity – internal or external characteristics – inclusions – in a gemstone that are byproducts of gemstone formation. These are sometimes considered flaws. They can be used to identify individual stones. Mined and synthetic gems can have inclusions.
Color – when grading diamonds, color ranges from nearly colorless to tints of yellow or brown. Traditionally, the whiter or more colorless the diamond, the greater the value. Mined and synthetic gems develop with these gradations. Simulants are purposefully created colorless or with a variety of different colors.
Conflict diamond - As per the United Nations definition, conflict diamonds are “rough diamonds which are used byrebel movements to finance their military activities, including attempts to undermine or overthrow legitimate Governments.”
Conflict-free diamond - There is no single definition of conflict-free diamonds. Rather, definitions begin with the UN definition as a baseline, diamonds NOT use to "finance military activities," often adding more stringent criteria addressing human rights.
Cut – the style, shape, proportions and relationship with light of gemstones are determined by the skill of the cutter or detail of the cutting process in conjunction with the crystalline attributes of the uncut stone. Grading is based on how the cut optimizes beauty and overall appeal.
Diamond – a crystalline carbon that is the hardest known mineral, is usually nearly colorless, that when transparent and free from flaws is highly valued as a precious stone, and that is used industrially, especially as an abrasive. Diamonds can be mined or lab-created, either process creating stones with identical chemical composition.
Inclusions - internal or external characteristics of a gemstone that are byproducts of gemstone formation. These are sometimes considered flaws. They can be used to identify individual stones. Quantity and size of inclusions are used to determine clarity. Mined and synthetic gems can have inclusions. Simulants do not.
Kimberley Process – a joint governments, industry and civil society initiative to stem the flow of conflict diamonds – rough diamonds used to finance wars.
Lab-created – refers to gemstones NOT originating from a mine. Can refer to identical, synthetic, simulant or stones similar to mined gemstones.
Lab-grown – refers to gemstones NOT originating from a mine. Most often refers to identical, synthetic or simulant gemstones.
Mined – refers to stones mined from a cave or mining pit or retrieved from the surface when unearthed by wind or water erosion.
Real – refers to gemstones which are naturally occurring or chemically identical to naturally occurring stones. Often the term is used in marketing by mined stone providers to imply a lack of authenticity in lab-created stones. This misperception is gradually changing.
Similar – an infrequently used term which refers to stones whose appearance is similar to mined or synthetic stones. The chemical composition is often significantly different; Color, Cut and Clarity can vary; visual characteristics can change over time as in clouding; hardness can be significantly lower. Examples include glass, cubic zirconia, moissanite and other forms.
Simulant – refers to manufactured gemstones chemically different from naturally occurring gemstones but which appear the same to the unaided eye. Simulants can be manufactured to any Color, including colorless; have the highest Clarity as the manufacturing process does not create inclusions; can be Cut in any form and often with greater light-capturing properties than mined or synthetic stones. Some simulants are nearly as hard as diamonds.
Synthetic – refers to manufactured gemstones chemically identical to mined gemstones. Synthetics emerge from the manufacturing process as naturally occurring stones and must be graded for Carat, Color, Clarity and Cut, often authenticated by the same organizations which verify grades of mined gems.