| It is possible to buy Tanzanite in a myriad of | | | | magnification. In SI1 they are usually visible and |
| different places and mediums in this age of | | | | SI2 quite visible to the unaided eye. Typical |
| communication. One of the more recent and | | | | inclusions are included crystals, large liquid |
| possibly most risky of places is the internet. It | | | | inclusions, feathers, dense clouds. |
| offers up a virtual cacophony of opportunities to | | | | I1-I2-I3: The lowest grade. Stands for Imperfect. |
| purchase this much revered gemstone but no | | | | These stones are characterised by inclusions that |
| benchmark as to what is a good buy and what is | | | | have a negative effect on either appearance, |
| not. This article endeavours to arm the reader | | | | durability or both. At I1 there is a moderate |
| with a working knowledge of what they should be | | | | effect on either factor, I2 a severe effect on |
| looking for when attempting to buy a Tanzanite, | | | | either factor and I3 a severe effect on both |
| either on the internet or in a more traditional | | | | factors. |
| setting such as a jewelry store. | | | | In terms of Tanzanite, a top stone must be VVS. |
| When purchasing Tanzanite there are several | | | | Any lesser clarity grade will affect the value |
| main factors you need to consider - these are | | | | downwards and denotes a lower grade stone. |
| the 4 c's - Color, Clarity, Carat Weight and Cut. | | | | CARAT WEIGHT |
| COLOR | | | | Tanzanites exist even in the 100+ carat range but |
| Color is the most important of the 4 C's when | | | | these are rare. Generally stones are in the below |
| considering Tanzanite quality. It can also be one of | | | | 1 - 10 carat range. Carat weight affects the price |
| the most confusing aspects as you surf the web | | | | generally as weight increases stones in the same |
| as so many different sites use different terms | | | | quality bracket will cost more per carat. |
| grading systems and it is difficult to effectively | | | | CUT |
| compare one with another. | | | | Although it has the least impact on value of the 4 |
| COLOR GRADING SYSTEM | | | | C's cut is still important. In the market, tanzanites |
| There is only one universally accepted official | | | | are found in a variety of shapes and cutting |
| grading system for colored gems and that is the | | | | styles. Ovals and cushions are the most common, |
| GIA system (Gemological Institute of America). | | | | but rounds are also seen, as are other shapes, |
| However, there are numerous trade based | | | | including emerald cuts, trillions, etc. Cabochon-cut |
| systems as you will see when surfing the web. | | | | tanzanites are not often seen. Cuts should be |
| The majority of these are very subjective and | | | | proportional - you don't want to pay for a stone |
| vary widely. One of the terms commonly used | | | | with alot of weight in the pavilion for example |
| (and misused) in the trade is AAA Tanzanite. This | | | | when this weight will be invisible in a setting. |
| is a term used by the miners to denote the very | | | | OTHER CONSIDERATIONS |
| top grade of Tanzanite - the very deeply | | | | FAKES / SYNTHETICS / IMITATIONS : Tanzanite |
| saturated exceptional stones. Only 1% of all | | | | has never been synthesized, but a number of |
| Tanzanite is this grade and this very deep color | | | | imitations exist. The most common is blue-violet |
| saturation is very hard to come by. | | | | glass. A synthetic fosterite has also been used as |
| The GIA grade for these stones is bV 6/5 and | | | | an imitation and is known as Tanzanique in the |
| vB 6/5. As color is such a visual medium I cannot | | | | trade. It has a lower RI than Tanzanite and does |
| give an adequate synopsis of the different color | | | | not have the same pleochroism so is easily |
| grades in this article but there is a very useful | | | | distinguished from the real thing. However, laymen |
| resource on the Lapigems Gem Company | | | | can easily be fooled so always buy from a |
| website by clicking on the various links under the | | | | reputable dealer, preferably a member of the ICA |
| heading "Tanzanite Education" on Lapigems | | | | (International Colored Gemstone Association) |
| Gemstone Company website. You will be treated | | | | which has a strict code of ethics. |
| to a multimedia presentation using moving pictures | | | | ENHANCEMENTS: Virtually all gem tanzanite of a |
| which will give you a very good visual exposure | | | | blue violet color has been heat-treated to enhance |
| to what to look for in terms of color as well as | | | | the color. In the rough state most Tanzanite is |
| tone and saturation charts illustrating how the GIA | | | | predominantly brown. Heating at 500 to 600 |
| system works with color and what to look for in | | | | degrees centigrade causes this colour to change |
| terms of how it applies to Tanzanite. | | | | to blue. This is a permanent and stable change. |
| I will now move on to the second most important | | | | LIGHTING: A great deal of Tanzanite marketing |
| consideration - clarity. | | | | makes a big deal of the "red flash" phenomenon |
| CLARITY | | | | of Tanzanite. This is one of the features of the |
| Clarity is the second most important of the 4 c's | | | | stone and is due to Tanzanite's trichroism. |
| when considering Tanzanite quality. Clarity simply | | | | Tanzanite is extremely light sensitive, with |
| refers to how inclusion-free a gemstone is. Once | | | | incandescent lighting (yellow lighting found in |
| again, the most universally accepted and most | | | | common light bulbs) tending to shift its color to |
| documented system is the GIA system but there | | | | the violet side causing the red and pink flashes to |
| are also numerous other trade based systems in | | | | appear within the stone. |
| use. The basic rule with Tanzanite is that it should | | | | WHAT IS BLOCK D TANZANITE?: Block D |
| be at least eyeclean but preferably loupeclean too. | | | | Tanzanite is a term commonly used in marketing |
| Top stones are loupeclean. Below is a chart | | | | Tanzanite. Block D simply refers to the area from |
| showing the GIA clarity grading system. | | | | which material is mined. The Tanzanite mining area |
| VVS VS SI1 SI2 I1-3 | | | | has been divided into 4 blocks by the Tanzanian |
| VVS: This is the top grade in the GIA system. | | | | government - Blocks A to D. Traditionally, larger |
| Tanzanite is classed by the GIA as a "Type 1" | | | | quantities of the best material was found in block |
| gem which means it is graded very strictly. | | | | D so the term became synonymous with the top |
| Stands for Very very slightly included and whilst | | | | grade. However, it has become a bit of a |
| most VVS Tanzanites are flawless they can | | | | marketing ploy recently and is a term misused as |
| contain minute inclusions which are difficult to see | | | | it implies that only block D produces the AAA |
| with a loupe (10x magnification) and invisible to the | | | | grade. This is not the case - AAA comes from all |
| unaided eye. Typical minute inclusions may be | | | | blocks, block D has traditionally just produced |
| very fine needles, tiny hairline feathers, very faint | | | | more of it than the others. It is best to ignore |
| clouds and percussion marks. | | | | the term as it is simply a marketing ploy and it is |
| VS: This stands for Very Slightly Included and | | | | largely misused. It is better to use more scientific |
| these stones are characterised by minor inclusions | | | | and official grades like the GIA system than to |
| which are somewhat easy to see under 10x | | | | rely on subjective trade terms. |
| magnification but usually invisible to the unaided | | | | This article has tried to cover all the main points |
| eye. Typical inclusions may be small included | | | | that should be taken into account when buying |
| crystals, liquid inclusions, fine needles, small | | | | Tanzanite. Undoubtedly there will be others I have |
| feathers | | | | missed but if these basic tenets are adhered to |
| SI1 - SI2: This stands for Slightly Included and | | | | and understood, the minefield of Tanzanite |
| these stones are characterised by noticeable | | | | purchase should be a safer place. |
| inclusions which are apparent under 10x | | | | |