Technical Data for DIAMOND.
name: DIAMOND
colour: Colorless, yellow, brown, sometimes green, blue, reddish, black
colour of streak: None possible
mohs hardness: 10
specific gravity: 3.47 - 3.55
cleavage: Perfect
fracture: Conchoidal to splintery.
crystal system: Isometeric ( cubic ); mainly octahedrons, also
rhombic dodecahedrons, cubes, twins, plates.
chemical composition: C, crystalised carbon.
transparency: Transparent.
refractive index: 2.417 - 2.419
double refraction: None, often anomalous.
dispersion: 0.044
pleochroism: None.
absorption spectrum: Colorless to yellow: 4780, 4650, 4510, 4350, 4015,
4230, 4155, 3900 Blue-green: ( 5370 ), 5040, ( 4980 )
fluorescence: Variable; Colorless and yellow: mostly blue. Brown
and green: often green.
GRANULATION.
Granulation is so called because of the practise of using tiny
spheres no larger than grains, or granules in the
process. Simply put granulation is done by
preparing gold granules of the same size, these are
then glued in place with a mixture of organic glue
(such as gum tragacanth), and a powdered copper
bearing material (such as cupric hydroxide, cupric
oxide, or cupric acetate). once the glue has dried
the whole item is heated in a reducing atmosphere
(such as a charcoal fire). during the heating the
glue gets driven off as carbon dioxide, the copper
bearing material reduces to metallic copper, and
the metallic copper then alloys itself with the
parent metal. This causes the surface of each
granule to have a slightly lower melting
temperature than the parent metal, but only at
their contact points, and these contact points then
"fuse" together before the whole object melts.
You can tell Granulation by it's characteristic gaps
between the granules. If the granules have been
soldered in place, the gaps will be flooded by solder.
Granulation was brought to it's highest form by
the ancient Etruscans, who used beads, or granules
down to a size of 1/240th. of an inch. They used
to build not only nice flat decorative patterns
with these beads, but actually stacked them to form
small three dimensional figurines.
Wal.
