THE MINERAL SPINEL

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Spinel is a very attractive and historically important gemstone mineral. Its typical red color, although pinker, rivals the color of ruby. In fact, many rubies of notable fame belonging to crown jewel collections were found to actually be spinels. Perhaps the greatest mistake is the Black Prince's Ruby set in the British Imperial State Crown. Whether these mistakes were accidents or clever substitutions of precious rubies for the less valuable spinels by risk taking jewelers, history is unclear. The misidentification is meaningless in terms of the value of these gems for even spinel carries a considerable amount of worth and these stones are priceless based on their history, let alone their carat weight and pedigree.

Today, expensive rubies are still substituted for by spinel in much the same way a diamond is substituted by cubic zirconia. Not to commit a fraud or theft but to prevent one. Spinel may take the place of a ruby that would have been displayed in public by an owner who is insecure about the rubies safety. The spinel probably is still valuable but better to lose a $100,000 dollar spinel than a $1 million dollar ruby!

Spinel and ruby are chemically similar. Spinel is magnesium aluminum oxide and ruby is aluminum oxide. This is probably why the two are similar in a few properties. Not suprisingly, the red coloring agent in both gems is the same element, chromium. Spinel and Ruby also have similar luster (refractive index), density, and hardness. Although ruby is considerably harder (9) than spinel, spinel's hardness (7.5 - 8) still makes it one of the hardest minerals in nature.

Spinel may be the poorer cousin of ruby, but its pinker color and other qualities make it attractive in its own right. Spinel typically forms nicely proportioned octahedrons. But it is famous for a type of twinning that bears its name, the Spinel Twin Law. Spinel Law twinning is also found in other isometric minerals such as diamond, galena, cristobalite, magnetite, franklinite and other members of the spinel group. This type of twinning produces a twin plane that is parallel to one of the octahedral faces. The plane acts as a mirror plane and produces a left and right side that are mirror images of each other. This may not sound all that spectacular for a very symmetrical mineral like spinel which is loaded with mirror planes. However this mirror plane is not parallel to any of the others and actually lowers the symmetry of the crystal (only in appearances though).

A good description of the twin is hard to explain, but here it goes. The plane falls (of course) in the center of the crystal, dividing it in half. The two octahedron faces parallel to the twin plane are equilateral triangles. Each point of the triangles is doubled across the twin plane with an indentation between them. The crystal looks like it has trigonal symmetry, but the three indentations are a clue that this crystal is a twin. Twins of spinel are rare, but their popularity makes them readily available on the market.

PHYSICAL CHARACTERISTICS:

  • Color is red, green, blue, purple, brown, and black; but red is by far the more common color.
  • Luster is vitreous.
  • Transparency: Crystals are transparent to translucent and sometimes nearly opaque.
  • Crystal System: Isometric; 4/m bar 3 2/m
  • Crystal Habits include the typical octahedron, but can be found as dodecahedrons and combinations of other isometric forms. Also as rounded grains in alluvial placer deposits.
  • Cleavage: None
  • Fracture is conchoidal.
  • Hardness is 7.5-8.0
  • Specific Gravity is 3.6-4.0
  • Streak is white.
  • Other Characteristics: index of refraction is approximately 1.71 - 1.76 and rutile inclusions may produce six or four rayed stars or asterisms.
  • Associated Minerals include calcite, dolomite, corundum and garnets.
  • Notable Occurrences include Burma, Sri Lanka, Brazil and Afghanistan.
  • Best Field Indicators are twinned crystals if present, color, hardness, density and locality.
Spinel Jewelry - Hover over an item for more information
Rock Crystal and Black Spinel Bracelet in Sterling Silver
This smart rock crystal and black spinel bracelet balances clear rock crystal with black spinel for a seamless day-to-night transition. Sterling silver bracelet.Only $115.00 at Ross-Simons
no photoRock Crystal and Black Spinel Bracelet in Sterling Silver
$115.00
Ross-Simons
Turquoise and Black Spinel Ring in Sterling Silver
Get a big-spender look at a nice low price. Vivid blue cabochon of stabilized turquoise is poised in perfect contrast to black spinel trim. Sterling silver ring.Only $100.00 at Ross-Simons
no photoTurquoise and Black Spinel Ring in Sterling Silver
$100.00
Ross-Simons
5.00ct t.w. Black Spinel, .60ct t.w. Diamond Buckle Bangle Bracelet
An RS exclusive. A fun design with glittering contrast. 5.00 ct. t.w. black spinel bangle features an Art Deco-style buckle of .60 ct. t.w. diamonds. Box clasp and hinge, sterling silver bracelet. Diamond birthstones are the perfect gift for April...Only $385.00 at Ross-Simons
no photo5.00ct t.w. Black Spinel, .60ct t.w. Diamond Buckle Bangle Bracelet
$385.00
Ross-Simons
Green Onyx and Black Spinel Statement Ring in 18kt Gold Over Sterling
So dramatic and full of dynamic vitality, this large round green onyx ring showcases the central green onyx in a double frame of stunning black spinel. 18kt gold over sterling silver ring.Only $175.00 at Ross-Simons
no photoGreen Onyx and Black Spinel Statement Ring in 18kt Gold Over Sterling
$175.00
Ross-Simons
Black Spinel, .60ct t.w. Multi-Stone Marquise Earrings in Silver
These marquise earrings have an exotic aura, centering .30 ct. t.w. of marquise tanzanites in frames of .30 ct. t.w. white topaz and black spinel Post/clutch, sterling silver earrings.Only $84.00 at Ross-Simons
no photoBlack Spinel, .60ct t.w. Multi-Stone Marquise Earrings in Silver
$84.00
Ross-Simons
Black Spinel Octopus Pin Pendant Necklace, Ruby Accents. 18"
Our mysterious deep-sea diva octopus pendant necklace peeks out from ruby-accented eyes. Paved with black spinels, the pendant can also be worn as pin. Includes a rope chain with a springring clasp. Revolver safety. Sterling silver pin pendant necklace.Only $135.00 at Ross-Simons
no photoBlack Spinel Octopus Pin Pendant Necklace, Ruby Accents. 18"
$135.00
Ross-Simons
.85ct t.w. Multi-Stone Citrine Giraffes Pin Pendant Over Sterling
Savanna sweethearts. These giraffes make a sweet pin pendant, decorated with .85 ct. tot. gem wt. citrines, smoky quartz, and diamonds with black spinel eyes. Double bale fits up to a 2mm chain, sold separately. Revolver safety. 18kt gold over sterling...Only $195.00 at Ross-Simons
no photo.85ct t.w. Multi-Stone Citrine Giraffes Pin Pendant Over Sterling
$195.00
Ross-Simons
.16ct t.w. Citrine, .15ct t.w. Diamond Owl Pendant Necklace. 18"
This owl pendant necklace will be a whimsical addition to your jewelry collection. Our fine feathered friend perches in a leafy frame, glittering with .16 ct. t.w. citrines and .15 ct. t.w. diamonds. Black spinel accent eyes. Hinged bale suspends from...Only $157.50 at Ross-Simons
no photo.16ct t.w. Citrine, .15ct t.w. Diamond Owl Pendant Necklace. 18"
$157.50
Ross-Simons
Multi-Stone Cameo Necklace in Gold Over Sterling. 18.5"
This multi-stone cameo necklace showcases a detailed blue magnesite cameo trimmed with .70 ct. t.w. iolites on a strand of black spinel and pyrite beads. Lobster clasp, 18kt yellow gold over sterling silver necklace.Only $85.00 at Ross-Simons
no photoMulti-Stone Cameo Necklace in Gold Over Sterling. 18.5"
$85.00
Ross-Simons
Italian 20.55ct t.w. Amethyst, Black Spinel Ring in Silver
An attention-getter, for sure! This 17.50 carat amethyst cabochon is set with 3.05 ct. t.w. amethyst baguettes on the sides and 2.55 ct. t.w. black spinels all over. Made in Italy. Sterling silver ring with black rhodium finish. Amethyst birthstones...Only $276.50 at Ross-Simons
no photoItalian 20.55ct t.w. Amethyst, Black Spinel Ring in Silver
$276.50
Ross-Simons
Black Spinel, .90ct t.w. Citrine Tiger-Stripe Ring, White Topaz Over Sterling
We love this wild style's flashy stripes. The tiger-stripe ring get its glow from black spinels, .90 ct. t.w. citrines and .20 ct. t.w. white topaz. 18kt yellow gold over sterling silver ring. Citrine birthstones are the perfect gift for November...Only $135.00 at Ross-Simons
no photoBlack Spinel, .90ct t.w. Citrine Tiger-Stripe Ring, White Topaz Over Sterling
$135.00
Ross-Simons
Green Onyx, Black Spinel Earrings, White Topaz in Gold Over Sterling
A fanning floral design gives these earrings some character, with an intriguing contrast of green onyx, black spinels, and .30 ct. t.w. white topaz. Post/clutch, 18kt yellow gold over sterling silver earrings.Only $165.00 at Ross-Simons
no photoGreen Onyx, Black Spinel Earrings, White Topaz in Gold Over Sterling
$165.00
Ross-Simons
Black Spinel, .63ct t.w. Multi-Stone Bug Pin Pendant Necklace. 18"
An RS exclusive. This little bug pin pendant necklace makes quite the statement with black spinel and .63 ct. tot. gem wt. of smoky quartz, citrines, and diamonds. Includes a rope chain with springring clasp. Revolver safety. Sterling silver pin...Only $195.00 at Ross-Simons
no photoBlack Spinel, .63ct t.w. Multi-Stone Bug Pin Pendant Necklace. 18"
$195.00
Ross-Simons
5.80 ct. t.w. Multi-Stone Owl Ring in 18kt Gold Over Sterling. Size 6
This 5.80 ct. t.w. multi-stone owl ring is all dressed up with a 5.50 carat amethyst and .30 ct. t.w. white topaz trim. Black spinel eyes. 18kt rose gold over sterling silver ring. Amethyst birthstones are the perfect gift for February birthdays.Only $100.00 at Ross-Simons
no photo5.80 ct. t.w. Multi-Stone Owl Ring in 18kt Gold Over Sterling. Size 6
$100.00
Ross-Simons
Black Spinel, .11ct t.w. Diamond Highway Ring in Gold Over Sterling
An RS exclusive. This black spinel and .11 ct. t.w. diamond highway ring is black, white and gleaming all over. Rows of .11 ct. t.w. diamonds and black spinel cross, adding glamour and contrast to this chic 18kt yellow gold over sterling silver ring.Only $155.00 at Ross-Simons
no photoBlack Spinel, .11ct t.w. Diamond Highway Ring in Gold Over Sterling
$155.00
Ross-Simons
This Site Awarded
Available SPINEL specimens:
see this List of ALL specimens including SOLD ones
 

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