1. The 4 C's (Carat, Color, Clarity, Cut): These are the most important factors:
* Color:
* Most Valuable: Intense, vivid, deep violet-blue. The stronger and purer the blue, the more valuable.
* Less Valuable: Lighter shades, brownish undertones, or more dominant purple.
* Trichroism: Tanzanite is trichroic, meaning it shows three different colors depending on the viewing angle: blue, violet, and red. The most desired stones show strong blue and violet.
* Clarity:
* Highly Valuable: Eye-clean tanzanite (no inclusions visible to the naked eye) is most desirable.
* Less Valuable: Stones with visible inclusions (internal flaws) will be less valuable.
* Carat: Larger stones are rarer and thus command a higher price per carat. The price increases significantly as the carat weight increases. For example, a 5-carat stone will be worth *much* more per carat than a 1-carat stone of similar quality.
* Cut: A well-cut stone will maximize the brilliance and color of the tanzanite. Poorly cut stones will appear dull and lifeless and be worth less. The cut should also be symmetrical and proportioned correctly.
2. Treatment:
* Nearly all tanzanite is heat-treated. This is a standard practice that enhances the blue color. Heat treatment itself is not considered negative and is usually not disclosed, unless done artificially.
* Untreated tanzanite: Is exceptionally rare. Because virtually all tanzanite is heated, untreated material commands a significant premium.
3. Origin/Mining:
* Location: Tanzanite is only found in a small area of Tanzania, near Mount Kilimanjaro. This rarity is part of its appeal.
* Ethical Sourcing: As with all gemstones, ethically sourced tanzanite is becoming increasingly important to consumers and will often command a higher price.
4. Market Conditions:
* Supply and Demand: Like any commodity, the price of tanzanite is influenced by supply and demand.
* Economic Factors: Economic downturns can affect the demand for luxury goods like gemstones.
General Price Ranges (Estimates):
These prices are *very* rough estimates and depend heavily on the quality of the stone. They are per carat.
* Low Quality (Pale color, visible inclusions): $75-$150 per carat.
* Medium Quality (Good color, minor inclusions): $150 - $400 per carat.
* High Quality (Intense color, eye-clean): $400 - $700+ per carat.
* Exceptional Quality (Very intense color, flawless or near flawless, large size): $700 to $1,000+ per carat (and potentially much higher for exceptional stones).
Where to get an accurate appraisal:
* Independent Gemologist: The best way to get an accurate appraisal is to take your tanzanite to a qualified, independent gemologist. They can assess the stone's color, clarity, cut, and carat weight, and provide an estimate of its value based on current market conditions. Make sure they are not associated with any retail store, as this could lead to bias.
* Reputable Jeweler: Some reputable jewelers who specialize in colored gemstones can also provide appraisals.
Important Considerations:
* Online Prices: Be very cautious about buying tanzanite online without seeing it in person. Photos can be misleading, and it's difficult to assess the true color and clarity from a picture.
* "Too Good to Be True" Prices: If a price seems too good to be true, it probably is. Be wary of scams and misrepresented stones.
* Certificates: A certificate from a reputable gemological laboratory (such as GIA, AGTA, or EGL) can provide assurance about the authenticity and quality of the stone. However, certificates alone do not guarantee value.
In summary, determining the worth of tanzanite requires careful evaluation of its color, clarity, cut, carat weight, treatment, and market conditions. Consulting a qualified gemologist is the best way to get an accurate appraisal.