3 - Clarity, Cut, and Carat Weight Flashcards
Clarity
A gemstone’s relative freedom from inclusions and blemishes.
Blemish
Characteristic or irregularity confined to the surface of a polished gemstone.
Inclusion
A characteristic enclosed within a gemstone, or reaching its surface from the interior.
Clarity Characteristic
Internal or external feature of a gemstone that helps determine quality.
What three value factors is clarity related to?
Appearance, durability, and rarity.
What determines the influence of inclusions on value?
Size, number, position, color/relief, nature
Break
Classified as inclusion. The three kinds ore cleave, parting, and fracture.
Cleavage
A smooth, flat break in a gemstone parallel to planes of atomic weakness. Results from vulnerability in a gem’s structure.
Which kind of break is the most threatening?
Cleavage.
In which gemstones is it common to see cleavage?
Topaz, tanzanite, moonstone, and diamonds.
Parting
A flat break in a gemstone parallel to a twinning plane.
Twinning Plane
Location of a change in direction in a gem’s crystal structure, established during growth.
Fracture
Any break in a gem other than cleavage or parting. Often have scalloped shape.
When do fractures occur?
During growth or the mining process.
How can a fracture’s appearance be mitigated?
Fill with resin or epoxy.
Fluid inclusions
Small pocket in a gem that’s filled with fluids and, sometimes, glass bubbles and tiny crystals. Can affect a gem’s appearance, value, and ability to endure jewelry processes.
Included crystal
A mineral crystal trapped within a gem as it grows.
Eye-clean
When a gem’ inclusions are visible only under magnification.
Examples of typically eye-clean species
Aquamarine, citrine, kunzite, tanzanite, topaz
How is the value of a typically eye-clean gem affected by inclusions?
In the case of eye-clean gems, a stone will be more affected by the presence of inclusions than on typically visibly-included stones.
Helpful inclusion
An inclusion that contributes to a pleasing optical effect.
Silk
A group of fine, needle-like inclusions; helpful in cat’s-eye, star corundums, and fine blue sapphires.
What are two types of helpful inclusions?
Silk and horsetails
Horsetails
Wisps of long, gold, fiber-like inclusions that radiate from a central point. Present in demantoid garnets.