Buying Guide of Tourmaline Gemstones and Mineral Group
Tourmaline with variety of colours is widely liked by people around the world. In fact, now a days these are popular gemstones for sales. People are looking for tourmaline gemstones for sale curiously especially if they are of facet grade. If you are looking for wholesale gemstones and mineral shop online, you will get lot of tourmaline offers online. Here it becomes difficult to make a choice. Today we will highlight some information about buying guide of tourmaline gemstones and mineral group. It will give you some basic understanding about tourmaline which will help you in buying tourmaline gemstones for sale online.
Tourmaline A Mineral Group
Tourmaline is not a single variety of gemstone. It is a group of minerals. There is no individual name for tourmaline in the gemology. All forms of mineral group are called tourmaline. The word tourmaline is derived from the Sinhalese word “tura mali,” which means, “stone mixed with vibrant colors.”. Tourmaline is a very popular crystal and gemstones for sale.
It has variety of colours. Almost every colour comes in tourmaline. The colour ranges from red to pink, green, blue, magenta to tea-blue, meadow – green to vibrant yellow, black, Paraiba colour, bi colours, yellow and many other colours. Black tourmaline is also popular in tourmaline varieties. Even this is common observation that no any tourmaline has same exact colour. every piece will be different from each others. It is famous as a “magic” stones.
The colour variety is the unique aspect of tourmaline crystals. It comes in all colours, red, green, yellow, orange, blue, bi colours, indigo, sea green, black, and multicolored. It is a group of minerals from chemical and physical point of view. The Elbaite mineral is the member of tourmaline group. Others are Liddicoatite, Dravite and Schorl. They are hardly used as gemstones.
Physical and Chemical Information of Tourmaline Gemstones and Mineral
|Chemical Classification||Boron silicate|
|Chemical Composition||As tourmaline belongs to several minerals so it has unique formulas categories.
A simple generic formula for the Tourmaline group is:
(Ca,Na,K,[vacancy]) (Li,Mg,Fe+2,Fe+3,Mn+2,Al,Cr+3,V+3)3(Mg,Al,Fe+3,V+3,Cr+3)6 ((Si,Al,B)6O18) (BO3)3(OH,O)3 (OH,F,O)
|Color||Colorless, blue, neon blue, indigo, red, green, yellow, orange, pink, purple, gray, black, sea green, multicoloured,|
|Transparency||Transparent to opaque|
|R.I (Reflective Index)||1.616 – 1.650|
|S.G||2.9 – 3.3|
|Hardness||7 – 7.5|
Following can help in the identification of tourmaline. Here they are.
- The crystals of tourmaline are always prismatic with many striations that are parallel to each others in their long axis.
- They have 6 sides cross sections having rounded edge which are often triangular.
- Colour zones are found in their their cross-sections or along their length.
- The tourmaline crystals are plechroic. Darker colours can be viewed down the C-axis. Lighter colour can be viewed perpendicular to the C-axis.
Famous Varieties of Tourmaline
- Indicolite or Indigo lite: This variety from light blue to dark blue colour.
Paraiba Tourmaline: Paraiba colour is a neon blue colour. This is highly desirable variety and expensive one. Paraiba is Paraiba, Brazil. It has trace elements of copper.
Rubellite: This variety is from pink to dark red. Often it is close to ruby colour. That is why it is called rubellite.
- Watermelon Tourmaline: The watermelon like pattern are found in this variety of tourmaline. The center will be red and border will be green. There are many other colours are ground in this variety like pink / orange, black/ blue.
- Cat’s Eye Tourmaline: This type of variety has cat’s eye effects.
- Chrome Tourmaline: This is very popular varity of tourmaline and expensive also. It has deep green colour caused by chromium impurities.
- Achroite: Colorless variety
Schorl: This is black tourmaline variety.
- Colour Change: This variety often changes colour i.e. green in daylight and red in incandescent light.
- Bi-Color: tourmaline crystals which have 2 or more colors in the same piece of stone.
Colours of Tourmaline Gemstones
In colour, tourmaline leaves behind all othere stone. No all tourmaline will have same colour. Every piece will be different from each others. It is found in more hues, nuances, shades. Even tourmaline have many colours in single piece sometimes. Tourmaline comes in blue, dark blue, bi colour, green, black, yellow, purple. pink, ruby colour, red, orange, greenish blue, bluish green, sea green, light blue, dark pink.
Treatment in Tourmaline
Tourmaline is normally heated or irradiated. It is done so to enhance the color of the tourmaline gemstones and crystals. Mostly treatment is done after cutting and polishing. However people do treatment tourmaline crystals in mineral specimen form also. Treatment is difficult to detect in the tourmaline.
Geological Occurrence of Tourmaline Gemstones and Minerals
Tourmaline are usually found in igneous and metamorphic rocks. They usually occur as an accessory mineral. They take formation in fractures and cavities during hydro-thermal activity. This is hard stone. During sedimentary process, they can bear the resistance in streams.
Where tourmaline is found?
Brazil is producing tourmaline from the last 500 years. Commercially, tourmaline was mined in 1821 in the United States followed near the town of Paris, Maine. Other countries, where tourmaline is found are in Namibia, Afghanistan, Pakistan, Mozambique,Nigeria, Tanzania, the United States and other countries. Here gem quality and mineral specimen form of tourmaline is found.
Tourmaline as a gemstone for sale?
The prices of tourmaline depend on size, colour, clarity. The most expensive tourmaline is Paraiba, indicolite and bi colours. Paraiba however is the most expensive than even later two. Prices can go from $50 to $1000 per ct in the rare and big sizes. The others can be from $6 to onward per carat.
When you look tourmaline for sale, look for its size also. Paraiba is rare in 2ct above. Similarly chrome tourmaline also comes in small sizes. Others can be till 10 ct or more.