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354 Glossary
Skip. A bucket employed in narrow or inclined mine shafts, where the hoisting device must be confined between guides.
Smaragdus. Ancient name for emerald and other green stones.
Sorters. The experts at the South African diamond mines who assort the rough diamonds.
Sorting Tables. Tables on which rough diamonds are assorted.
Specific Gravity. The relative weight of bulk as compared with distilled water at 60° F.
Spectrum. The
coloured image or images produced when the rays from any source of
light are decomposed or dispersed by refraction through a prism.
Splints. Thin, pointed pieces of diamonds.
Spread. Surface in proportion to the depth of a stone.
Star Stones. Sapphires,
and sometimes rubies, which by structure and cutting are seen to be
asteriated, exhibiting a star of six rays of light.
Step-Cut. (Trap-Cut.)
A form of cutting employed for stones not deeply coloured when they are
not cut as brilliants; a simple typical form is that of a stepped
pyramid with the apex sliced off.
Streak. Colour of the surface of a stone after being rubbed or scratched. "Streak-Powder" is the powder abraded from a stone.
Striated. Term
applied to minerals which exhibit lines traversing the plane of a
crystal; such lines bear a definite relation to certain forms of the
mineral on which they occur.
Subtranslucent. When the edges of a mineral only transmit light faintly.
Table-Stone. The
typical form thus described is a style of diamond-cutting derived from
an octahedron by cutting to opposite corners to an equal amount.
Tailings. The
refuse part of washed gem ground, rock, or gravel which is thrown
behind the tail of the washing apparatus and which is put through a
second process to recover values possibly remaining.
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