Tanzanite Clarity Information and "Type" Grading

Any discussion of tanzanite gems would be remiss if it did not include information regarding clarity grading of the different types of gemstones found in nature. We discuss the 4 C's in the second section. The issue of gemstone clarity is best summed up as follows:

"There is hardly a gemstone which is completely "clean." Most of the time, they contain foreign matter or some kind of dislocation or irregularity in the crystal lattice. Sometimes only under the microscope can these "flaws" be discovered. In the lingo of the trade, one does not speak of flaws, but rather of inclusions, because the term flaw has a derogatory meaning that is not justified.

Since inclusions are not accidental appearances but rather are subject to strict conformities with natural law, they can tell a lot about the origin of the gemstone deposits and, in addition to that, they help in their identification. Even though each gemstone has its individual inclusion history, there are nevertheless forms of inclusions which can be grouped together and can be associated with specific gemstone types and/or gemstone imitations."

(excerpted from Gemstones of the World, pg. 49, Schumann; Amazon $24.95)

Schumann's excellent presentation on gemstone clarity and inclusion is worth the price of the book in and of itself and we highly recommend this book for your personal gemstone library. The book is thoroughly readable and is a valuable tool because of the information it contains.

Schumann alluded to gemstones being "grouped together" in terms of clarity and the following chart helps to understand this grouping a bit better by gemstone types:

The key to understanding clarity in tanzanite is that it most commonly occurs free from inclusions, so when it is graded under 10x magnification, very rigid guidelines are present for a stone to be considered flawless or nearly so.

Not so is the case with emeralds. They normally occur in nature with a moderate number of inclusions, therefore as a Type III stone the clarity scale is re-defined to compensate for this difference.

In summary, different Types (I, II, III) of gemstones should be compared to their peer group of stones before determining value. From the above chart, a slightly included Type III stone will appear more included than a slightly included Type I stone. Please let us know if you have any questions on this concept.

Grading & Clarity - Part II General Information

Understanding the 4 C's; Color, Cut, Clarity, Carat

If you have been to a local jeweler recently, you probably are already acquainted with the 4 C's. Many clients can remember a few of the C's, but not all, so we dedicate a few words to this important topic... perhaps the most important topic regarding colored gemstones. The 4 C's are Color, Cut, Clarity, and Carat Weight . These are the most important criteria when considering a gemstone purchase. Other factors influencing value are durability, rarity, market demand, and wearability. For the purposes of this discussion, we need to take a look at the 4 C's.

Color

As specialists in colored gemstones, we would like to stress the primary importance of color in your purchasing decision. Color is "king" or the most important aspect when considering purchasing a gem. Color is generally the earliest impression we have of something and our perception of that something is generally what remains with us. The richness of tone and hue also play a major role in determining gemstone value.

Please consider the following scenario: Let's say you are comparing two 7x5mm oval blue tanzanites. The first gem shows a pale to medium blue coloration, good cutting, is very clean, and has a weight of 1.18ct. The second tanzanite shows a strong violetish blue color, fair to good cutting, is slightly included, and weighs in at 1.05ct. Which one should you choose? The answer is undoubtedly tanzanite #2. The first gem wins in every category except the most important... color! Due to its superior color, tanzanite #2 will generally appraise for substantially more per carat than tanzanite #1. As we talk to clients, private collectors and jewelers, this recurring topic presents itself frequently. Too many people have been caught up in what we term the "clarity craze." Yes, clarity is important, but please consider color 1st in your purchasing decision. As a caveat to this discussion, we only offer the best of color and clarity in gemstones.

Cut

Many clients overlook this important area. The criteria of Cut dovetails nicely with Clarity. Much has been said and written about this important topic, for without good cutting, even the finest colored gems beauty and value will be sacrificed.

Cutting standards exist for each gem shape. There are certain angles for each gem material that must be used to bring out the true brilliance and beauty of a stone. The faceter's primary objective is to evaluate the rough gem and orient it so that the best color will present itself when the stone is completed. This is not an easy task, especially due to the fact that a piece of rough may not be "cuttable" when oriented the best way for color. Take, for instance, Zircon. To cut this natural gemstone properly, its brilliance is critically dependent upon orientation. Special instruments are used to determine this for the most part, though many faceters have an "eye" for it. At times, the proper orientation may be opposite to a cutting plane preventing a good yield. Unfortunately, most faceters will orient the stone for yield resulting in a dingy, sleepy color. The World's top cutting houses would rather discard rough than to produce a gem that is not cut to a high standard.

Once the proper orientation for the rough has been determined and the shape has been selected, it is now time for the faceter to cut the gem. As mentioned previously, there are certain "critical angles" specific to each type of gem that must not be violated in this difficult process. Compound these requirements with the fact that the faceter still has to polish the gem to a perfect finish and you can see how difficult this process is.

Most native cut tanzanites are cut with step pavilions as opposed to brilliant pavilions. Once again, the primary directive at the mine sites is to cut for yield. We once considered purchasing a particularly well-colored piece of tanzanite. It was so richly colored, that it was difficult to pass up. Everything was ideal on this stone except its cut. It had a faceted corner to repair some damage and the overall proportions of the gem were less than ideal. Quite simply, the stone should have been refaceted before it was marketed for sale. We did pass on this gem and settled up with the wholesaler on some other richly colored tanzanite that possessed better cutting. Yes, color is "king", but if the cutting so seriously detracts from a gem's beauty, it is often better to avoid such purchases and keep in the hunt for something better.

Clarity

The beginning of this page contains a discussion on the issue of clairty and how different types of gemstones are categorized before the clarity scale is applied to them. The thing to keep in mind is that tanzanite occurs frequently in nature as flawless or nearly flawless, therefore tanzanite is subjected to very stringent guidelines when graded for clarity.

Carat Weight

As you may have read elsewhere, tanzanite is much less expensive than blue sapphire in just about every size. We routinely see 3 to 4 carat sapphires offerred in the $5000+/ct. range and we have even seen sapphires over 10cts. offerred at over $15,000/ct. Tanzanite, therefore, represents a very good value for the consumer. We offer the follow guidance on appropriate tanzanite sizes for setting in jewelry.

• Tanzanite Earrings > up to 2.5 carats each stone
• Tanzanite Rings > up to 15 carats, depending upon the desired look/statement
• Tanzanite Pendants > up to 50 carats
• Tanzanite Collection > sky's the limit!

Finally, we always recommend that you purchase the highest quality color in tanzanite with secondary considerations given to size. In other words, always invest in exceptional color first, and then obtain the largest stone your budget will allow.