Top 10 Special Effects of Gemstones

Cristina — Sat, 03 Jan 2009 16:12:33 +0000

Precious Stone Optical Special Effects

Gemstones’ special effects are the either natural – called “phenomena” by gemologists – or created by the special cutting and shaping techniques. These special techniques add brilliance to the defiance of the stone itself and give optical impression. Below there is a list of popular gemstone effects that are often used for better stone definition:

1. Fire

Fire is defined as the color of highlights because is the ability of the stone to draw light apart into its constituent colors, due to dispersion. Zircon and diamond are among those stones that show elaborated fire abilities.

2. Schiller

Schiller is also known as play of color, in which the interior of a stone displays flickers of color as it is moved in the light. Opal is especially valued for this trait. There is no actual object inside the stone. This special effect arises from light interference within the micro structure of the mineral.

3. Fluorescence

Fluorescence is the ability of a mineral to turn incoming light of ultraviolet color into light of a visible color. Is a condition of vigor and freshness. A special effect like this is desirable to transform the dull color of a stone to a different glow.

4. Labradorescence

Labradorescence arises from light interference within microscopically thin layers of twinned crystals. The sizes and orientations of these twin lamellae are consistent in this feldspar mineral, thus colors are considered strong and limited with regards to its direction and orientation.

5. Color change

Some gemstones have certain color changes especially when put in different aspects of light especially when faced with sunlight. This is due to a gemstone’s ability to absorb wavelengths strongly. Change of color is not the same as the changes in color with crystal orientation that affects tourmaline and iolite, which are due to the optical property called pleochroism.

6. Iridescence

Iridescence represents all sorts of rainbow effects ( schiller and labradorescence are varieties of iridescence ) Mother-of-pearl is the most familiar example of iridescence, but it is also found in fire agate and some obsidian as well as many artificial gems and jewelry.

7. Cat’s Eye

Derived from the French term “chatoyance”. Cat’s eye is caused by impurities within the gemstone arranged like fibers and line up forming axes. Quartz is famous for its cat’s eye property when struck by light. Traces of fiber within the mineral give this effect a special twist.

8. Aventurescence

Inclusions in a gemstone are usually considered flaws. But in the right kind and size, inclusions create internal sparkles, particularly in quartz (aventurine) where the special effect is called aventurescence. Thousands of tiny flakes of mica or hematite can turn plain quartz into a glittering rarity or feldspar into sunstone.

9.Opalescence

Opalescence is also called adularescence and milkiness in other minerals. It can be a white haziness or soft colorations. Opal, moonstone (adularia), agate and milky quartz are the gemstones best known for this special effect.

10. Asterism

When fibrous inclusions align on all of the crystal axes, the cat’s eye effect can appear in two or three directions at once.

The other October Birthstone: Tourmaline

Cristina — Thu, 25 Sep 2008 19:18:38 +0000

Did you know?

There are 14 officially recognized varieties of tourmaline.
Tourmaline can have different colors from black, green, pink, yellow, light blue, dark blue, and colorless. Some crystals of tourmaline can contain more colors.
Various colors of tourmaline
The most famous type of multiple coloration is the watermelon tourmaline; it typically changes from red to green in a concentric color zonation, usually from the center out.
Green tourmaline crystal

Pink and green watermelon tourmaline
A colorless variety of tourmaline, achroite, is very rare.
Achroite Colorless Tourmaline
Tourmaline has a hardness of 7-7.5 on the Moh’s hardness scale. Tourmaline is about the same hardness as sand and dust, thus tourmaline is not recommended for use in rings and bracelets for everyday wear.
The name Tourmaline comes from the Sinhalese (Sri Lanka) word tura mali which translates as the stone of mixed colors.
The most expensive tourmalines are the blue indicolite, green verdelite and pink rubellite.
Cat’s Eye Tourmaline presents a “cat’s eye” effect similar to what is usually observed in tiger’s eye cabochons.
Cat's Eye Tourmaline
Ancient legend says that tourmaline is found in all colors because it travelled along a rainbow and gathered all the the rainbow’s colors.
Tourmaline is believed to strengthen the body and spirit, especially the nervous system, blood, and lymph. It is also believed to inspire creativity and was used a lot as a talisman by artists and writers, as “the stone of muse”.
When it is warmed or rubbed, it attracts small bits of paper, lint and ash, usually very light things. This occurs because the gem becomes charged with static electricity.
The stone is known as the “peace stone,” meant to dispel fear and make its wearer calm.

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