Spinel – Synthetic

By admin | No Comments

Refractive Index : 1.728 (+0.012 – 0.008)

Optical Characteristic : SR, ADR

Specific Gravity : 3.64 (+0.02 – 0.12)

Formula : MgAI2O4

Crystal System : Cubic

Variety/Species : All

Species/Group : Synthetic spinel

Birefringence : none

Dispersion : .020

Hardness : 8

Toughness : good

Ultrasonic : Usually safe

Steam : usually safe

UV Long : Inert to strong

UV Short : Inert to strong

Pleochroism : None

Strength : N/A

Pleochroism Colors : None

Heat : May change color

Acids : No reaction

Light : stable

Polish Luster : vitreous to subadamantine

Fracture : conchoidal

Fracture Luster : Vitreous

Clarity Type : N/A

Tones : N/A

Saturations : N/A

Cause of Color : Blue – iron, cobalt; Red/pink – chromium

Enhancements : none

Cleavage : None

Color Range : Colorless, blue, yellow, green, Violet, orange, (rare), pink, red, (rare) opaque dark blue (lapis lazuli imitation) Violetish, bluish, greenish, yellowish, orangy, pinkish, reddish

Transparency : Transparent to opaque Usually transparent.

Phenomena : Color change

Separations : Spinel – Synthetic from-
Natural spinel: RI (except red and blue), magnification, polariscope reaction,
fluorescence (except red and pink)

Natural Red Spinel: magnification

Natural blue Spinel: magnification, spectrum, polariscope reaction, fluoriscence,
color filter reaction (possibly)

All corundum: RI, SG, birefringence, optic character, magnification, fluorescence, spectrum

Identifying Characteristics and information
Cross hatch effect in polariscope, gas bubbles, curved striae in red variety.

Spectral Data
Typical of dopant used. Natural blue spinel has 4600 band due to iron(not currently seen in syn. spinel).

Trade Names and Misnomers
Alumag
Aqua Gem (M)
Aquagem
Berylite
Brazilian emerald (M)(2)
Corundolite
Dirigem
Emerada
Hope sapphire (M)

Posted in Natural Gemstones, Spinel Group, cubic