Karat
A variation of the word "carat", (used to describe the weight of a gemstone), "karat", with a "k" is used to describe the purity of gold. Gold is often alloyed with silver, copper, and/or other metals to improve its strength and durability. Products made from gold are marked to show how much actual gold is contained in the product. Items marked 24K are 100% pure gold. Items marked 18K or 750 have 750 parts gold out of 1000, or 75% pure gold. Items marked 14K or 585 have 585 parts out of 1000, or 58.5% pure gold. Much of the jewelry manufactured before the 20th century do not have these marks and must be tested to determine purity.

Karatclad
Karatclad is a trademark for a very thick gold electroplating process; this type of plating is about 14 times thicker than standard electroplating.

Karu
A costume jewelry company formed in 1940, Kaufman (the comedian Andy Kaufman's parents) and Ruderman, Inc, New York, NY. The Karu pin above is paste (glass stones) and enamel on gold-plated metal.

Keeper Ring
A keeper ring is a ring which is used alongside another, more valuable ring to keep it securely on the finger.

Ketoh
See Bow Guard.

Keum Boo
A jewelry-making technique from Korea where 24k gold foil is fused to sterling silver.

Keystone
A keystone is a stone cut the shape of a keystone in an arch. Keystones are usually step cut. The costume jewelry manufacturer Schreiner uses keystones in many of its pieces.

King Cut
The king cut is a modification of the brilliant cut which is used for large diamonds. This cut has 86 facets.

Klein, Anne
Anne Klein (1923-1974) was an influential and popular American fashion designer. Anne Klein jewelry and buttons have been manufactured by the Swank Inc. since 1981. Anne Klein's logo is a lion's head on a square tag.

Knife Wire
An extremely thin wire holding a gemstone making it appear to float.

Knot
A knot is a flaw (a mineral inclusion) in a gemstone (usually a diamond) that is ar the surface of a gem after polishing. The know is a small raised bump on the finished gemstone.

Koh-oh-i-nur
The Koh-i-Nur (meaning "Mountain of Light") is one of the largest-known diamonds. It was found in India and belonged to the first Indian Rajahs of Malwa (in the 1300s). The gem made its way to Persia in the 1500s (taken as a spoil of war by the Mogul Sultan Babur). At some point it was returned to Indiabut was taken by the East India Company and presented to Queen Victoria of England in 1850. Tge gem was later cut and set into a brooch and later into the State Crown of the United Kingdom. The Koh-i-Nur is part of the crown jewels of England and is kept in the Tower of London, London, England.

Korite
See Ammolite.

Koroit Opal
Opals from the Koroit mines in Australia. These are the hardest of the boulder opal types and often referred to as "Koroit picture opals" because of the patterns.

Kramer
Kramer was a high-quality costume jewelry company founded by Louis Kramer in 1943. He was then joined by his brothers Harry and Morris. Some of their pieces are marked 'Kramer,' others are marked, 'Kramer of New York.' Kramer made jewelry for the Dior company during the 1950's. Kramer went out of business in the 1970's. The fish pin above is by Kramer.

Kunzite
Kunzite is a transparent pink, light pink, or light purple gemstone that resembles roze quartz. It is a variety of the mineral spodumene. Kunzite can fade after prolonged exposure to light. Kunzite is also called "evening stone," because of its propensity to fade in bright light. The original color of some kunzite stones can be restored or even intensified by irradiation. It is usually used as a large stone and is easily chipped; small stones of kunzite are difficult to cut. Kunzite is often used in pendants. Kunzite has a hardness of 6-7 and a specific gravity of 3.1 - 3.2. Kunzite was first found in 1902 in Pala, California, USA, and is named for the gemologist George F. Kunz. Kunzite's chemical composition is LiAlSi2O6

Kyanite
Kyanite is a deep sapphire blue, green, gray, or white gemstone. The color is not always uniform; it can be blotchy or in streaks. The cystals are crystals are transparent to translucent. Kyanite has a hardness of 4.5 to 6.5; the hardness varies depending on which way it is scratched (this happens because kyanite consists of long, thin crystals). It has a specific gravity of 3.58. Kyanite is found in Brazil, Burma, Kenya, Europe, India, Australia, Kenya, and the USA. Kyanite's chemical composition is Al2SiO5; it is composed of andalusite and sillimanite.