Garnet

Garnet: Pros & Cons of Identification and Valuation — Mounted vs Unmounted

By Karen Howard — Jewellery Appraisers Coach

Garnet has a talent for surprising people. Most jewellery owners think of it as the deep red birthstone of January, inexpensive and common. But in reality, the garnet family includes some of the most fascinating and valuable gems on the market — from vivid tsavorite to colour-change garnet and even rare demantoid with horsetail inclusions.

For appraisers, garnet presents both opportunities and challenges. Identification can be more complex than first glance suggests, and accurate valuation requires confidence in variety, quality and setting considerations. Whether the stone is loose or mounted will change how you approach the work.

Let’s explore the pros and cons.

The Garnet Family — A Quick Refresher

Garnet isn’t a single gemstone. It’s a group containing multiple species and varieties, frequently found in blends. Some well-known examples include:

•Pyrope — typically deep red

•Almandine — darker red to purplish-red

•Spessartine — orange to reddish-orange

•Grossular — green, yellow, colourless, brown

•Tsavorite — bright green grossular variety

•Hessonite — cinnamon orange grossular variety

•Demantoid — highly refractive green andradite garnet

•Rhodolite — pyrope-almandine blend, purplish-red

Different varieties bring dramatically different price points — which is precisely where valuation gets interesting.

Identifying Garnet: Pros & Cons

Pros

✔ Readily identifiable properties

Refractive index, specific gravity, and absorption spectra are generally reliable indicators when the stone is unmounted. However, some properties are off the capabilities of some instruments,

✔ Inclusion patterns can help

For example, chrysotile “horsetail” inclusions are strongly associated with demantoid, adding both value and confidence.

✔ Minimal enhancement concerns

Garnet is rarely treated, making valuation more straightforward once identification is secure.

Cons

✘ Extensive overlap

Many garnets sit between species. This can complicate identification without advanced instruments.

✘ Wide range of colours and appearances

Rhodolite vs pyrope? Grossular vs hessonite? Andradite vs demantoid? It’s easy to mis-classify.

✘ Mounted identification limits

When a stone is set, refractive index, birefringence, and SG testing may be restricted or impossible, increasing uncertainty.

Valuing Garnet: Pros & Cons

Pros

✔ Strong market demand for premium varieties

Tsavorite and demantoid can command high values, especially with excellent colour and clarity.

✔ Good stability and durability

With a hardness between 6.5–7.5, garnet generally withstands wear and protects value over time.

✔ Attractive to collectors

Unusual colours (mint, purple, colour-change) increase desirability.

Cons

✘ Huge price variation

Low-value red almandine vs high-value tsavorite — you must know exactly what you’re looking at.

✘ Mounted stones hide clarity and cutting issues

Inclusions, chips, windowing and weight estimation become harder to assess in metal.

✘ Limited pricing data

There are fewer structured market comparables compared to diamonds or sapphires. Research time increases.

Mounted Garnet — Special Considerations

Pros

•Preserves the stone’s condition

•Shows intended colour and brilliance in natural presentation

•May provide age, origin and authenticity clues based on mounting style

Cons

•Restricted access limits testing

•Accurate weight estimation becomes essential

•Valuation may depend more heavily on reportable assumptions and disclaimers

•Risk of misidentification increases

For premium greens and collector stones, you may advise the client that removal is required — or refer to a trusted gem lab.

Unmounted Garnet — Special Considerations

Pros

•Clearer visibility for inclusions, cut quality and colour zoning

•Full access to refractometer, hydrostatic SG testing, UV response and filters

•Weight certainty increases valuation confidence

Cons

•Loose stones may have chips or abrasions

•Easy to mix up varieties if unlabelled

•Market for loose garnet is more variable than mounted retail

Unmounted gems give you better science; mounted gems give you better context. Both matter.

The Appraiser’s Advice to Clients

When clients ask about value, here are simple guidelines:

1️⃣ Not all garnet is created equal

The variety, colour, clarity and cut matter enormously.

2️⃣ Certificates may be worthwhile

Especially for tsavorite and demantoid.

3️⃣ Condition counts

Wear, chips, abrasions and durability influence value.

4️⃣ Market demand fluctuates

Rhodolite is strong at retail, tsavorite performs well at auction, hessonite and spessartine depend on quality.

5️⃣ Mounted vs loose changes the process

Set expectations that testing, and value ranges may differ.

Final Thoughts

Garnet is one of the most rewarding gems to appraise — when you know what you’re looking at. With varieties ranging from everyday jewellery to museum-quality collector stones, correct identification is the foundation of correct valuation.

Whether the stone is loose or mounted, the appraiser’s role remains the same: apply science, maintain curiosity, protect the client, and stay aware of market reality.

And above all — never underestimate garnet.