Labels

Gemology ...


What is Gemology

Gemology or gemmology is the science, art and profession of identifying and evaluating gemstones. It is considered a geoscience and a branch of mineralogy. Some jewelers are academically trained gemologists and are qualified to identify and evaluate gems.

What Are Natural Gemstones?

Natural gemstones are delivered to us courtesy of nature, with no interference from humans. By the time they appear in our jewelry they've been cut or polished, but they've not been altered in other ways.
What Are Genuine Gemstones?
A genuine gemstones is the real thing, but isn't natural anymore if it was treated in some way to enhance its appearance.
Enhancements allow jewelry manufacturers to improve the look of gemstones that consumers wouldn't otherwise purchase. Treated gemstones are genuine, but they are no longer considered natural. If naturally "perfect" stones were the only ones available, most of us couldn't afford them.
What Are Synthetic Gemstones?
A synthetic gemstone shares a natural stone's physical, chemical and optical qualities, but it is created in a laboratory. It's kind of like making a high tech batch of cookies -- we know the ingredients and we know how long to cook them. There are synthetic versions of nearly all popular gemstones and many versions have been available for a long time. Older synthetics were fairly simple for gemologists to detect, because they were often too perfect. Some modern synthetic gemstones look more natural and are more difficult to identify, but an experienced jeweler or gemologist can usually classify them.
Jewelry that includes quality synthetic gems can be just as beautiful as jewelry made with natural stones. Good synthetics aren't always inexpensive, but should cost much less than natural stones of similar quality.
Since synthetic gemstones have the same composition as their natural counterparts, they could technically be called genuine, but that would be considered deceptive labeling if the stone's origins are not disclosed. Question the ethics of anyone who knowingly omits origin information, and the expertise of anyone who cannot provide it.

The Rainbow of Gemstones:


In red, you have the choice not only of ruby, but also tourmaline, spinel, or garnet. In green, there is not only emerald and jade, but also tourmaline, tsavorite garnet, andperidot. The wide range of gemstones available today means that no matter what your favorite color is, a gemstone is available to match it in your price range.


Birthstone - Gemstone mapping

By Month:
February - Amethyst
March - Aquamarine , Bloodstone
July - Ruby
December - Blue Topaz,Turquoise, Tanzonite

By Day:
Monday - Pearl
Wednesday - Amethyst
Friday - Topaz
Saturday - Sapphire


Many people decide to go with jewelry that combines several birth stones into one item, a birthstone bracelet, for example. Others prefer single stones. The birthstone chart, below, will take you to either an article or a merchant site where you can get more information on that particular birth stone.
Birth MonthModern BirthstonesTraditional BirthstonesMystical BirthstonesAyurvedic BirthstonesOther Birthstones
Garnet
Garnet
Amethyst
Bloodstone
Amethyst
Bloodstone
Diamond
Quartz, White Sapphire
Emerald
Sapphire
Alexandrite
Moonstone
Opal
Ruby
Ruby
Ruby
Carnelian
Sapphire
Jade
Sapphire
Agate
Moonstone
Lapis Lazuli, Diamond, Chrsolite
Tourmaline
Opal
Pink Tourmaline, Zircon, Aquamarine
Citrine
Topaz
Diamond
Zircon, Turquoise,Lapis Lazuli
Ruby


Day Of Birth Gemstones:




If you were born on:Your Day-Of-Birth Gemstone Is:
SundayTopaz
MondayPearl
TuesdayGarnet
WednesdayAmethyst or Cat's Eye
ThursdayEmerald (Similar color gem in semi-precious is Peridot)
FridayTopaz (See Blue Topaz, Smoky Topaz)
SaturdaySapphire (Similar color semi-precious: Iolite)





Diamond Simulants

The high price of gem-grade diamonds has created a large demand for materials with similargemological characteristics, known as diamond simulants or imitations. Simulants are distinct from synthetic diamond, which unlike simulants is actual diamond, and therefore has the same material properties as natural diamond. Enhanced diamonds are also excluded from this definition. A diamond simulant may be artificial, natural, or in some cases a combination thereof. While their material properties depart markedly from those of diamond, simulants have certain desired characteristics—such as dispersion and hardness—which lend themselves to imitation. Trained gemologists with appropriate equipment are able to distinguish natural and synthetic diamonds from all diamond simulants, primarily by visual inspection.


Diamond Simulants => moissanite, cubic zirconia(CZ), rhinestones(high-leaded glass)
moissanite is almost 10% of Diamond price(Diamond Hardness = 10, Moissanite hardness = 9.5)

Moissanite is also brighter, more lusterous, and has more fire than diamond.These criteria define how "pretty" the jewel is - the shine, the sparkle, and the prismatic qualities.It is artficially made not natural.

Cubic zirconia (or CZ) is the cubic crystalline form of zirconium dioxide (ZrO2). The synthesized material is hard, optically flawless and usually colorless, but may be made in a variety of different colors. It should not be confused with zircon, which is a zirconiumsilicate (ZrSiO4).



Mohs scale of Mineral Hardness

The Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer material. It was created in 1812 by the German mineralogist Friedrich Mohs and is one of several definitions of hardness inmaterials science. The method of comparing hardness by seeing which minerals can scratch others, however, is of great antiquity, having first been mentioned by Theophrastus in his treatise On Stones in ca 300 BC, followed by Pliny the Elder in his Naturalis Historia circa A.D. 77.

Mohs Scale of hardness is a RELATIVE scale, not proportional. I mean by this that a mineral with the hardness of 8 will NOT be twice as hard a a 4. (For example, diamond is 40X harder than sapphire!).It is really a scale of relative "scratchability".

#1 is softest..................#10 is hardest
#1Talc
#2Gypsum
#3Calcite
#4Flourite
#5Apatite
#6Feldspar
#7Quartz
#8Topaz
#9Corundum
#10Diamond


Gemstones and Mohs Scale

Diamond:....................10
Syth. Moissanite:........9.5
Corundum:..................9
Cubic Zirconia:............8.5
Spinel:........................8
Topaz:........................8
Emerald:.....................7.5 - 8
Almandite:...................7.5
Rhodolite:....................7 - 7.5
Pyrope:.......................7 - 7.5
Spessartite:.................7 - 7.5
Tourmaline:..................7 - 7.5
Iolite:...........................7 - 7.5
Quartz Group: .............7
Peridot:.......................6.5 - 7
Jadeite:.......................6.5 - 7
Andradite:....................6.5 - 7
Scapolite:....................6.5
Zircon (low):.................6.5
Tanzanite:...................6.5 - 7
Feldspars:...................6 - 7
Nephrite:.....................6 - 6.5
Opal:..........................5.5
Lazulite:.....................5 - 6
Lapiz Lazuli:...............5- 6
Turquoise:..................5 - 6
Stainless Steel...........5.5
Sphene:.....................5 - 5.5
Apatite:......................5
Rhodochrosite:...........4
Coral:........................3 - 4
Refractive Index


Refractive index, or RI as it is often abbreviated, is one of the most important signatures of a gemstone. Measuring refractive index is one of the first steps in identifying a gemstone, though some gemstones have similar refractive indices and additional tests are required for a definitive identification.
RI is the ratio of the velocity of light in air to the velocity of light through a transparent material. If light passes from air into a transparent material at an angle of incidence other than a 90 degree angle, it is deflected at a different angle (the coincident angle) according to the RI. Gemstones with higher RI are generally more brilliant than those with low RI, because more light is returned back out the top or crown of the stone, instead of passing through the bottom or pavilion. Diamond has an RI of about 2.4; quartz, about 1.54-1.55. The RI of most gemstones is easily measured using a simple optical instrument known as a refractometer.
Some gemstones are singly refractive: they have only one refractive index. Other gemstones -- in fact, most -- are doubly refractive: they have two different refractive indices. When a beam of light enters a doubly refractive gem, it is split into two beams, each travelling at a different speed and on a different path through the crystal. Birefringence is a measurement of the difference between the two refractive indices in gems that are doubly refractive, and it ranges from a low of .003 to a high of .287. Very few gemstones are singly refractive; in fact, the only well-known gems with that property are diamond, spinel and garnet.
The following chart lists the refractive indices for 126 varieties of gemstones, sorted in descending order.
Refractive Index of Metals
  • Platinum: 2.330
  • Titanium: 2.160
  • Copper: 1.100
  • Nickel: 1.080
  • Gold: 0.470
  • Silver: 0.180
Gems Classfication
Gemstones in the Elements class:

Gemstones in the Oxides class:

Variety: RUBY
Variety: SAPPHIRE
Variety: ALEXANDRITE
Variety: YELLOW-GREEN CHRYSOBERYL
Variety: CAT'S EYE CHRYSOBERYL

Gemstones in the Carbonate class:

Gemstones in the Phosphate class:

Gemstones in the Silicate class:

Variety: AQUAMARINE
Variety: EMERALD
Variety: GOSHENITE
Variety: HELIODOR
Variety: MORGANITE
Variety: RED BERYL
Variety: IOLITE
Variety: DEMANTOID
Variety: HESSONITE
Variety: TSAVORITE
Variety: PERIDOT
Variety: AMETHYST (violet)
Variety: CITRINE (yellow to orange)
Variety: PRASIOLITE (green)
Variety: ROCK CRYSTAL (colorless)
Variety: ROSE QUARTZ (pink)
Variety: SMOKY QUARTZ (gray to black)
Variety: LARIMAR
Variety: KUNZITE
Variety: HIDDENITE
Variety: INDICOLITE
Variety: TANZANITE

Gemstones in the Mineraloids class:

Variety: MOLDAVITE

Precious Metals (in the Elements class):



ref:




Labels:

Popular Posts