Field report · 865
What to look for in an opal: solid vs doublet vs triplet
Three opal product categories that look similar but have very different value — and how to tell them apart.
Opal is one of the more confusing stones for first-time buyers because the trade sells three different opal products under names that sound similar but represent very different value propositions.
The three categories
- Solid opal — natural opal cut from a single piece. Most valuable. The stone is opal all the way through; if you broke it, every fragment would still be opal.
- Opal doublet — a thin slice of natural opal bonded to a backing (often common opal, ironstone, or plastic). Provides the look of opal at lower cost. Visible "seam" at the bottom if you look at the edge.
- Opal triplet — opal slice + dark backing + clear protective cap (usually quartz or glass). Most economical. The top cap protects the thin opal layer from damage.
How to tell them apart
Look at the edge of the stone:
- Solid opal: uniform color and texture through the entire stone, even on the bottom
- Doublet: clear line visible on the side where opal layer ends and backing begins
- Triplet: two horizontal lines visible from the side — one at the cap-opal junction, one at the opal-backing junction
Some doublets and triplets have very thin opal layers (under 1mm). Hold the stone at an angle to a strong light; if the play-of-color seems to come from a very thin layer rather than from the depth of the stone, you're looking at a doublet or triplet.
Pricing
- Solid opal — $50/ct for commercial up to $20,000+/ct for top black opal
- Doublet — typically 30-60% of solid price for visual equivalence
- Triplet — typically 15-30% of solid price; lowest-cost opal product
Care implications
Care varies by construction:
- Solid opal — opal contains structural water; can craze if dehydrated. Store in moderate humidity. Avoid prolonged direct sunlight. Don't use ultrasonic cleaners.
- Doublet — same care, plus avoid prolonged water contact (the adhesive can fail)
- Triplet — most water-vulnerable. Don't soak. Don't expose to high humidity for extended periods.
Origin notes
- Australian opal (Coober Pedy, Lightning Ridge, Andamooka, Mintabie) — the world's primary commercial source; high-quality solid opal
- Ethiopian opal (Welo, Shewa) — newer market entry; bright play-of-color, but more hydrophane (water-affecting) than Australian
- Mexican fire opal — orange-red opal, sometimes faceted
- Honduran black opal — small-scale production
- Brazilian opal — typically less expensive Australian-style material
What to ask before buying
- Is this solid opal, doublet, or triplet?
- What's the origin?
- Has it been impregnated or treated?
- What's the play-of-color pattern — broadflash, pinfire, harlequin, rolling flash?
Honest sellers will tell you all of this. Sellers who get evasive about whether a stone is solid or doublet are not the sellers you want.