28/09/2026
When buying ruby & sapphire, most people only check whether the stone is heated or unheated.
But the real truth about gemstone treatments hides in the certificate Remarks section.
The word “Heated / Indications of heating” alone tells you very little.
Stones marked as heated can vary drastically in value:
✅ No‑heat
Natural, untreated corundum. Highest collectible premium.
✅ Traditional heating, no residues
Widely‑accepted industry enhancement. Stable for jewellery use.
⚠️ Heating with flux‑healing residues
Residues fill healed fractures. Higher residue level = significant value reduction.
⚠️ Beryllium diffusion treatment
Surface‑only colour treatment. Colour may disappear if the stone is re‑polished. Not traditional heating.
❌ Lead‑glass filling
Composite corundum, not solid natural gemstone. Very low market value.
Do NOT clean with ultrasonic. Keep away from heat & harsh chemicals.
GRS, GIA and SSEF each use different wording to describe these treatments.
Many sellers only mention “heated / unheated” without explaining what is written in Remarks.
Save this carousel to reference before your next coloured‑gem purchase 💎
We break down official lab comments from three top gem‑testing laboratories, with quick‑reference comparison chart.
Value hierarchy for same‑carat corundum:
No‑heat ＞ Traditional heating (no residues) ＞ Mild flux residues
⚠️ Avoid paying natural‑gem prices for beryllium‑diffused or lead‑glass‑filled stones.
Always read full certificate Remarks, do not rely only on verbal descriptions from sellers.
💎Save this post for your gem‑buying reference.
