Natural rutile has many times the fire shown by diamond, but it is masked by the red, brown or black body colour. The black material has been used in mourning jewellery, but rutile is most usually seen as rich, reddish brown, needle-like inclusions within quartz or within other stones, where the rutile crystals create a star effect by reflecting light.
Igneous and metamorphic rocks and alluvial deposits in Australia, Brazil, USA, Italy, Mexico and Norway.
Synthetic Rutile Properties
Chemical Composition:
Titanium Dioxide - TiO
2
Classification / Type:
The material is found abundant as inclusions (silk,
needles, crystals, etc.) in number of gemstones preferably in quartz, tourmaline, ruby and sapphire
but large facet table crystals are quite rare therefore gemological
importance lies in the synthetic counterpart produced by flame fusion
method.
Colors / Varieties:
All colors, generally colorless with a yellow tinge.
Crystal System / Forms:
Tetragonal System
Cleavage / Fracture:
Distinct
Optic Character:
Anisotropic,
D.R. ; Uniaxial Positive
Refractive Index / Birefringence:
2.616 - 2.903 / 0.287
Dispersion:
0.290 (high fire)
Magnification:
Generally clean, strong doubling giving a hazy appearance, dispersive fire
Cause of Color:
As per dopant used
Treatment (Enhancement):
Dark colored boules of synthetic rutile are heated
to give the light yellow color. Natural rutile is generally brown in
color which is heated to give yellow color.
Specific Tests:
Very high doubling and dispersive fire.
Synthesis:
Flame Fusion Method
Simulants (with separation tests):
G.G.G. (dispersion, doubling, S.G.),
Y.A.G. (dispersion, doubling), Synthetic Cubic Zirconia (S.G., dispersion, doubling), Diamond (dispersion, doubling), Strontium Titanate (dispersion, doubling), Sphene (doubling, dispersion, inclusions), Zircon (dispersion, spectrum), etc.
Geological Occurrence:
Natural rutile as inclusions in quartz, tourmaline and corundum. Synthetic rutile in a laboratory.
Cuts & Uses:
Facetted cuts, etc.
