Technical
Comparison of Emeralds
and Rubies
| Technical Data |
Natural Emeralds |
Chatham Created Emeralds |
| Chemical Composition |
Be3 (SiO3) |
Be3 A12 (Si03)6 |
| Chrystallographic Character |
Hexagonal habit - prismatic |
Hexagonal habit - prismatic |
| Hardness |
7 1/2 to 8 |
7 1/2 to 8 |
| Toughness |
Poor |
Fair - Depending on quality |
| Cleavage |
Very difficult |
Very difficult |
| Fracture |
Conchoidal |
Conchoidal |
| Specific Gravity |
2.67 to 2.75 |
2.67 to 2.75 |
| Streak |
White |
White |
| Melting Point |
2570°F |
2570°F |
| Acid Resistance |
All except hydroflouric |
All except hydroflouric |
| Degree of Transparency |
Transparent to translucent |
Transparent to translucent |
| Luster |
Polished surfaces are vitreous; fracture
surfaces are vitreous to resinous. |
Polished surfaces are vitreous; fracture surfaces are
vitreous to resinous. |
| Refractive Index |
1.565 to 1.599 |
1.560 to 1.565 |
| Birefringence |
.005 to .009 |
.003 to .004 |
| Optic Character |
Uniaxial - negative |
Uniaxial - negative |
| Pleochroism |
Green and bluish green; strong |
Green and bluish green; strong |
| Dispersion |
0.014 |
0.014 |
| Transparency to X-Rays |
Opaque |
Opaque |
| X-Ray Flourescence |
Dulled - weak |
Dulled - medium |
| Ultra Violet Flourescence |
Nil to orange-red (variable) |
Reddish-brown to red-medium to strong |
| Color Filter Reaction |
Red |
Red |
| |
| |
Natural Rubies |
Chatham Created Rubies |
| Color |
Medium to dark orangey-red to violetish-red |
Medium to dark violetish-red to red |
| Chemical Composition |
A12O3 |
A12O3 |
| Coloring Agent |
Cr2O3 |
Cr2O3 |
| Crystal System & Habit |
Hexagonal (rhombic) rhombohedron. Flat
types often in clusters |
Hexagonal (rhombic) rhombohedron. |
| Inclusions |
Included crystals, 'silk', fingerprints,
repeated twinning. No spherical gas bubbles. |
Veils, wisps, typical fingerprints; some have natural
ruby seeds. No spherical gas bubbles. |
| Phenomena |
Asterism and rarely chatoyancy. |
None |
| Specific Gravity |
4.00 + .03 |
4.00 + .03 |
| Hardness (Mohs) |
9 |
9 |
| Optic Sign & Character |
Uniaxial - negative |
Uniaxial - negative |
| Refractive Index |
1.762 to 1.770 |
1.762 to 1.770 |
| Pleochroism |
Strong dichroism red-purple and orange-red |
Strong dichroism red-purple and orange-red |
| Long-wave UV Flourescence |
Strong red |
Strong red |
| Short-wave UV Flourescence |
Variable, none to medium red |
Medium-strong red |
| Transparency to Short UV |
Opaque to UV below 3,000 A.U. |
Transmits UV of 2537 A.U. |
| Absorption Spectrum |
Lines or bands of absorption at A.U. 6942, 6928, 6680, 6592, 4764, 4750, 4685 |
Lines or bands of absorption at A.U. 6942, 6928, 6680,
6592, 4764, 4750, 4685 |
| X-Ray Flourescence |
Flouresces red, no |
Flouresces red with moderate |
| Phosphorescence |
Phosphorescence |
Phosphorescence |
| Growth Lines |
Straight |
Straight |
Inclusions in Chatham Created gemstones are a direct result
of natural crystal growth under minimal control by man. Slight
variations will occur inside the stone as well as on the
surface and are not considered defects. Similar inclusions
and surface breaks will often be found in the finest natural
emeralds and rubies in the world. Comparison chart information
furnished by the GIA.
Chatam Created gemstones are never oiled, manipulated or
treated in any way.
