M.o.M.i.:
the expanded
glossary
appendix a
BEHOLD... INCLUSIONS!
the museum of misfit inclusions: a glossary of the weird and wonderful
In case you haven't noticed: we're big fans of inclusions. Every gemstone is beautiful in its own way, but it's what's inside that counts. Inclusions are what truly make each gemstone one-of-a-kind, sometimes even influencing a gemstone's color, giving clues to a stone's origin or revealing treatment, and can even be the cause of certain optical phenomena.
Below is the full glossary of the many inclusions you might see in diamonds and sapphires.
APPENDIX A: THE EXPANDED GLOSSARY
a comprehensive guide all about inclusions in diamonds and sapphires
Diamonds
Bearding
Bearding occurs in round brilliant cut diamonds as a result of the bruting process, small hair-like lines that extend upward or downward from the girdle.
“Carbon Spots”
Black inclusions that appear in diamonds are often referred to as “carbon spots”; however, they are rarely carbon, but other black minerals usually pertaining to the amphibole or pyroxene groups (which are really just fancy words for other rocks).
Cavity
An indented opening where a crystal broke away or a feather opened up, usually the result of polishing.
Champagne
Champagne refers to diamonds that are predominantly brown, often with yellow or pink undertones. Champagne color is caused by the presence of nitrogen and/or distortion in the crystal lattice during growth. Champagne color is commonly measured on a scale of C1 (light champagne) to C7 or C8 (dark champagne/cognac).
Chip/Abrasion
Despite their hardness (diamonds = 10, sapphires = 9 on Moh’s scale of hardness), gemstones may experience damage due to human error or environmental factors; certain gemstones are naturally weaker due to their crystal axes (i.e.: diamonds, topaz), while others are brittle or susceptible to facet abrasion; we use words like “chip” or “fracture” to imply damage to a stone, while indented naturals and cavities occur naturally.
Cloud
A cluster of microscopic crystals or pinpoint inclusions can cause a hazy looking “cloud” inclusion.
Crystal
Inclusions in gemstones are often other gemstone crystals; for example, diamonds may have garnet, peridot or zircon crystals - or even other diamonds.
Fancy Black
Fancy Black color happens when a diamond has so many black inclusions causing it to be nearly or entirely opaque; black color is sometimes enhanced using irradiation. (Any treatments are disclosed in the product listing.)
Fancy Color
Not so much an inclusion, naturally occurring diamond colors are caused by the presence of specific elements, radiation or imperfections in the crystal structure.
Fancy Grey
Fancy Grey color in diamonds is caused by the presence of hydrogen (and sometimes boron).
Fancy White
Fancy White color in diamonds is caused by a high concentration of microscopic cloud-like inclusions.
Feather
A feather is an internal fracture in a diamond (or sapphire), often with a feathery appearance (hence the name); feathers can often cause a rainbow to appear inside a gemstone because of light travelling through trapped air and causing dispersion.
Girdle (Bruted vs. Polished vs. Faceted)
On round brilliant cut diamonds, the girdle (the outermost diameter of a diamond) is either bruted or polished. A bruted girdle has a rough, translucent appearance, and is created by rubbing two diamonds together when creating their round shape. A polished girdle is typically faceted after the bruting process. Some girdles are polished smooth.
Indented Natural
See Natural.
Knot
A crystal inclusion that reaches the faceted surface of the diamond.
Natural
A natural is a small area on the surface of a diamond that has intentionally been left unpolished in the cutting process, often to leave some unique feature that appeared on the rough crystal surface (such as a trigon), usually appearing near or on the girdle; an indented natural may also occur, a natural that extends inward, distinct from a chip.
Needle
A natural is a small area on the surface of a diamond that has intentionally been left unpolished in the cutting process, often to leave some unique feature that appeared on the rough crystal surface (such as a trigon), usually appearing near or on the girdle; an indented natural may also occur, a natural that extends inward, distinct from a chip.
Pinpoint
A microscopic crystal inclusion that appears only as a pinpoint through a jeweler’s loupe.
Rustic
“Rust” or “Rustic” are terms used to describe a diamond with rust-colored inclusions, typically caused by the presence of iron.
Salt & Pepper
Perhaps the most well-known of the imperfect Misfit Diamonds, the term Salt & Pepper refers to diamonds with many inclusions, such as feathers, clouds, or other minerals, with a black and white (or colorless) appearance like salt and pepper. These diamonds are sometimes referred to as ‘Galaxy,’ ‘Celestial,’ or ‘Grey’ diamonds (not to be confused with Fancy Grey diamonds, partly why we use the terms “Misfit Diamonds” as well as “Salt and Pepper Diamonds”).
Trapiche
A star-like pattern that occurs in diamonds when dark inclusions (usually hydrogen clouds) align with the crystal axis; most well-know for occurring in emeralds, trapiche patterns in diamonds are quite rare.
Trigon
A trigon is an indented triangle that appears naturally on the surface of a diamond crystal during the growth process; trigons can appear solitary or in groups, sometimes stacking within larger trigons.
Twinning Wisp
A wispy line of microscopic inclusions, either pinpoints or clouds, inside a diamond caused by irregular crystal growth.
Sapphires
Asterism
The optical phenomenon found in star sapphires, occurring when dense rutile inclusions cause the light to reflect a six-star pattern.
Color zoning
Areas of different color within a sapphire, often appearing along the hexagonal growth lines, or as distinct areas of color like in parti-color sapphires.
Crystal
Inclusions in gemstones are often other gemstone crystal, such as: hematite, calcite, mica, spinel or zircon.
Feather
A feather is an internal fracture in a diamond (or sapphire), often with a feathery appearance (hence the name); feathers can often cause a rainbow to appear inside a gemstone because of light travelling through trapped air and causing dispersion.
Fingerprint
Occurs in sapphires when healing happens during formation, a liquid-like inclusion resembling a fingerprint.
Growth Lines
Because sapphire crystals form as hexagonal prisms, hexagonal growth lines will often appear within a stone, as color zoning or with rutile forming along the crystal axes.
Opalescence
Typically caused when microscopic rutile silk inclusions cause the light to scatter, giving some sapphires an appearance like an internal glow.
Parti-color
A type of color zoning where two or more distinct colors within the same stone; sometimes referred to as bi-color sapphires, when the sapphire has only two colors.
Rutile
A mineral inclusion common in sapphires that forms as long needles; many parallel rutile needles have a "silk" appearance, often creating a sheen or opalescence, and the reason for asterism in sapphires.
Silk
A mineral inclusion common in sapphires that forms as long needles; many parallel rutile needles have a "silk" appearance, often creating a sheen or opalescence, and the reason for asterism in sapphires.
Zircon Halo
In heated sapphires, a zircon halo occurs when a zircon crystal inclusion bursts during the heating process, resembling a small, clear disc-like inclusion.
