Glossary M-R

Craft and Jewellery Glossary

This Jewellery Glossary includes industry terms and definitions in one convenient place. Click on letter below to go directly to the start of terms beginning with that letter.

Index M-R

M

mabe

"mabe" is a Japanese term and its literal translation is "half". A mabe pearl is a hemispherical shaped pearl (half sphere with one flat surface) which is grown against the inside of the oyster's shell, rather than within its tissue. Mabes occasionally appear in nature.

micron

Micron or micrometer equal to 1 millionth of a metre, or 1/25,000 of an inch. It is the unit of measurement to express the diameter of a wool fibre: the smaller the number, the finer the fibre. (A typical human hair is about 100 microns).

In terms of particles, relatively speaking, a grain of salt is about 60 microns and the eye can see particles to about 40 microns.

Micron as a unit of measurement is used in multiple areas of study including pore size of filters, contaminant size, diameter of fiber, film thickness, etc.

Millesimal Fineness

Millesimal Fineness is often just referred to as "fineness". This is a system to denote the purity of a precious metal (by parts per thousand) in an alloy. This includes precious metals like platinum, gold, and silver. For example, an alloy containing 75% pure gold is denoted as "750" fineness.

Millesimal fineness if usually rounded to a three figure number, especially when used as a hallmark or quality mark.

The millesimal fineness system is an extension of the older karat system.

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N

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O

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P

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Q

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R

rose

Roses are round Flat Backs^(defn) - they are loose crystal components that are round and have flat backs (undersides). Chatons ^(defn) on the other hand, though round in shape, do not have flat backs.

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