Sapphire & Ruby Heat Treatment
We heat sapphire and ruby rough to bring out color and improve clarity in stones that look pale or cloudy. Send us your material and we will examine it and let you know before we make a decision.
Color and clarity that were already in the stone
Heating natural corundum at high temperature dissolves the fine rutile needles known as silk and activates the trace elements sitting inside the crystal. Pale, gray or cloudy material can come out with stronger blue, pink or orange color and better transparency. Nothing is added to the stone. The change comes from what is already there.
Heat is an accepted treatment across the trade and the color it produces is permanent. We disclose it on every invoice, and on any lab report we arrange for you.
of the blue and pink sapphire on the market today has already been heat treated, by most industry estimates. It has been standard, accepted practice across the trade for decades.
What kind of rough benefits from heating
Heat needs something to work with. These are the kinds of sapphire and ruby rough we see real results on.
- Pale or washed out blue sapphire with a light body color
- Milky or silky material that reads cloudy because of fine rutile
- Geuda and semi geuda type corundum from Sri Lanka
- Color zoned stones where the color sits in bands or patches
- Grayish or greenish blue sapphire that needs the gray pulled back
- Pale pink and purple corundum that can move toward a cleaner pink
- Yellow sapphire that can be pushed to a deeper golden or orange tone
- Ruby rough that is dark, over silky or slightly opaque
- Fractured ruby and sapphire, where flux can help close surface reaching cracks
- Mixed parcels of low to mid grade rough that need sorting before anything is heated
How a stone responds also depends on where it is from. Montana sapphire usually goes straight into the furnace as is, since its crystal structure rarely needs any pre-shaping. Rough from most other origins, including much of what comes out of Sri Lanka, often needs some pre-shaping first to remove inclusions that could crack or shatter under high heat. Pre-shaping carries a small fee and takes a little weight off the rough, and we always check with you before doing it.
Material we would tell you to leave alone
Fine rough that already has good color and clarity is usually worth more unheated, and star material loses its star as soon as the silk goes. If a parcel looks like that to us, we will say so before anything goes near the furnace.
What to expect from heat treatment
Results depend on the material. Here is the honest picture of what heating does well, and where it runs out of room.
Color
High temperature heating usually deepens or shifts the color of corundum. Pale and gray sapphires can come out a strong blue or pink, and yellow stones can move toward gold or orange. The best results come from stones carrying iron and titanium. Very dark, near black sapphire often barely moves.
Clarity
Heat dissolves the microscopic rutile needles that make a stone look sleepy, so light passes through instead of scattering. On fractured material we sometimes heat with flux, which works into the cracks and closes them as the stone cools. That can make a large difference to how clean a stone reads.
Limits and risk
Not every stone improves. Material that is too clean already, or too heavily included, can come out looking much the same. Brittle rough with reaching fractures can break in the furnace. We check for that first and trim problem stones where it helps. Once a stone is heated the color is permanent and does not revert.
From your parcel to finished stones
Send us the details
Stone type, approximate weight and quantity, with photos in daylight if you have them. We come back with a rate and what we think the material will do.
Ship the rough
Tracked service, packed so the stones cannot rub together. Then send us the tracking number through the order form.
We sort and evaluate
The parcel is gone through stone by stone. Anything unlikely to change, or worth more unheated, is set aside and we write to you about it.
Heating
Heating is done in a Lakmini furnace, with electric kilns for material that needs a lower, closer controlled run. Ramp up and soak times are set to suit the rough.
Cutting
Almost every parcel we heat is cut here as well. Heated rough only shows what it gained once it is faceted or cabbed, and doing both here saves a shipping leg. If you would like the finished stones set into a ring, pendant or other piece, our jewelry team can take that on too.
Back to you
Finished stones go back by EMS or FedEx with tracking, once payment is settled. Everything leaves marked as heated.
Shipping and handling
Pack the rough so stones cannot knock against each other, and ship with a tracked service. EMS and FedEx are the two we recommend. Include a packing slip listing stone type, weight and quantity.
On the customs form, describe the contents as Mineral Rough Specimens under HSN code 710310, with a realistic declared value, and note on the invoice that the stones are being sent for heat treatment and cutting for re-export. Insurance is worth taking, since responsibility sits with the carrier once the package is handed over.
Once the package is on its way, send us the tracking number and shipment details through the order form.
This is a quick overview. Once you have spoken with us and decided to ship, read the full packing instructions, the customs and declared value guidance, and the invoice template on our Shipping & Payment page before you pack anything.
Return shipping
- EMSAround $85 including insurance, 14 to 21 working days
- FedExFrom $200, 4 to 5 working days
- TurnaroundShipped back within 4 to 7 business days of payment
- RatesSubject to change with carrier pricing
Ship to: Azard Fazahir, 246/3/111 Matale Road, Akurana, Sri Lanka 20850. Write the address exactly as shown.
Rates and quotes
Charges are based on the total carat weight of the parcel and the condition of the rough. We do not publish a fixed price list here because every lot is different, and cutting is quoted separately once we see what the stones look like after heating.
Tell us what you have
In most cases we can give you a rate from a few photos along with the weight and quantity. Send us:
- Stone type and origin if you know it
- Total weight in carats or grams
- Number of pieces in the parcel
- Photos in daylight, wet stones show color better
- Heating only, heating and cutting, or a finished piece set into jewelry
- A budget, if you are working to one
Questions we get most
What kind of results can I expect?
It depends on the material. Dull, gray or zoned sapphire often comes out with a much richer blue or pink, and silk that was clouding the stone usually clears. Some stones show very little change. We go through the parcel and tell you what we think before we start.
Can I get the heat treated stones cut as well?
Yes, and we would encourage it. Almost every heat treatment order we take is cut here as well, and there is very little reason to heat a stone and keep it in rough form. The color and clarity you gained only show properly once the stone is faceted or cabbed, and a buyer looking at heated rough is still guessing.
Doing both here also means one shipment out and one back, and a cutter who has seen exactly how the stone came out of the furnace. If you would like the finished stone set into a ring, pendant or other piece afterward, our jewelry team can take that on too. Ask about cutting and jewelry making when you send your parcel details.
How is the heating actually done?
We use a Lakmini furnace for most corundum, and electric kilns for material that suits a lower and more closely controlled run. Ramp up and soak times are set to suit the rough rather than run to a single fixed recipe, which is what keeps breakage down.
All work is done in house by cutters and treaters who have been doing it for years, and everything leaves here disclosed as heated.
Do you do beryllium or lattice diffusion?
No. We do conventional heat, with flux where the material calls for it. Diffusion treated stones have to be disclosed as diffused and generally hold very little resale value, so we stay with methods the trade accepts.
Will heating change the weight of my stones?
Heat itself takes off a negligible amount. Any real weight loss comes from trimming before heating or from polishing afterward, and we keep that as low as the stone allows.
Do heated colors last?
Yes. Unlike irradiation, color from heat is permanent under normal conditions. A properly heated sapphire keeps its color unless it is reheated or exposed to harsh chemicals.
How long does treatment take?
Parcels under 1000 carats usually take one to two weeks in the workshop, plus shipping each way. Larger parcels take longer, and cutting adds to that. We give you a timeframe with the quote.
How is the treatment disclosed?
Invoices are marked heated, and if you want the treatment noted on a lab report we can arrange testing before the stones ship back. Unheated stones with a report carry a premium, which is exactly why we tell you when a stone is better left alone.
What we can do next with your stones
Faceting
Precision faceting for heated and untreated rough, single stones through to production lots.
View details →Cabochon Cutting
Cabochons in standard and calibrated sizes, including star and phenomenal material.
View details →Jewelry Making
Set your heat treated and cut stones into a ring, pendant or other finished piece.
View details →Lab Testing
Independent lab reports arranged before your stones are shipped back.
View details →Send us photos of your rough and we will tell you what it can do
We work with miners, dealers, collectors and jewelers around the world, on single stones through to bulk parcels. Ask about cutting and jewelry making too, if you want the whole job finished here.