Education

Sapphires

From Kashmir cornflower blue to padparadscha — judging corundum across its colours.

Blue sapphire
01

What to look for in a sapphire

Sapphire is the mineral corundum in every colour except red (red corundum is ruby). At 9 on the Mohs scale it is the hardest gemstone after diamond, and it is expected to carry some inclusions. Colour dominates value: for blues, the market pays for a velvety, vivid blue of medium tone.
  • Colour — hue, tone, and saturation; vivid medium blues lead the market
  • Heat treatment — unheated stones of fine colour command a clear premium
  • Origin — Kashmir, Burma, Ceylon and Madagascar provenance carry historical weight
  • Clarity — fine silk (rutile inclusions) is normal and can sometimes improve colour
  • Fancy colours — pink, yellow, violet, and the rare padparadscha widen the field
What this means when you buy

We grade colour in calibrated daylight, against master stones — not under a jeweller's halogen, which flatters any sapphire.

What is a padparadscha?

A rare sapphire showing a delicate mix of pink and orange — the name comes from the Sinhalese word for the lotus blossom. Laboratories apply strict colour criteria before using the term.

What is silk?

Fine needle-like rutile inclusions. In moderation they scatter light softly and can give Kashmir-type stones their velvety appearance; in excess they cloud the stone.

World map of principal coloured gemstone deposits, including the sapphire sources Kashmir, Burma, Sri Lanka and Madagascar
02

Where sapphires come from

Origin is stated as a laboratory opinion based on inclusions and trace-element chemistry.
  • Kashmir — discovered in 1881 and effectively exhausted; they are usually a combination of saturated colour, velvety luster, and slightly hazy appearance.
  • Burma (Mogok) — renowned for their intensely saturated colours and clarity.
  • Sri Lanka (Ceylon) — the classic island source; the widest colour range, including padparadscha
  • Madagascar — the major modern source and accounts for nearly half of the world's supply.
  • Australia, Montana (USA) — renowned worldwide for their exceptional hardness (9 on the Mohs scale) and diverse colour palettes, particularly their moody, multi-colored parti gems and deep, rich teals, sea foam greens.
What this means when you buy

An origin opinion should always come from a laboratory with a deep reference collection — we would recommend two or more reports for high value stones.

Are Kashmir sapphires still mined?

The historical deposit is considered effectively exhausted — supply is essentially limited to stones returning to the market, which is what drives their prices.

Is Madagascar material inferior?

No. Madagascar produces stones that rival classic origins on beauty; they simply lack the historical provenance, which the market still prices.

03

Treatments: heat, and what must be disclosed

Most sapphires on the market — by most estimates the large majority — have been heated to improve colour and clarity. Heat treatment is stable, permanent, and accepted by the trade when disclosed. What changes the conversation is diffusion: lattice diffusion with beryllium can transform pale material into vivid yellows, oranges, or padparadscha-like colours, and must always be disclosed on the report.
  • No indication of heating — the premium category; wording matters on the report
  • Heated — accepted, stable, and the market norm; priced below unheated equivalents
  • Beryllium (lattice) diffusion — colour created by treatment; must be disclosed, priced far below heated stones
  • Surface diffusion and glass-filling — rare to see but exist at the commercial end; a recognised lab report protects you
What this means when you buy

We do not list diffused or filled sapphires in the catalogue. Every stone carries a current report stating its heat status in the laboratory's own words.

How can anyone tell a stone was heated?

Heating alters inclusions in ways visible under magnification — silk dissolves, crystals develop stress haloes. Laboratories read these signatures and state their conclusion on the report.

Is an unheated sapphire worth the premium?

For fine size, colour and clarity, yes — unheated stones are scarcer and hold value better. For commercial colour, a well-chosen heated stone is often the more sensible buy.

GRS
Gübelin
SSEF
AGL
GIA
04

Reading a sapphire report

A sapphire report should state four things plainly: natural or not, treatment status, colour and an origin opinion. Colour trade names — royal blue, cornflower — are laboratory-specific conventions, not universal grades, so note which laboratory issues them.
  • SSEF — Swiss Gemmological Institute, Basel; founded 1972
  • Gübelin Gem Lab — Lucerne; founded 1923, the oldest of the Swiss houses
  • GRS — GemResearch Swisslab, Lucerne; founded 1996, widely used in the coloured-stone trade
  • AGL — American Gemological Laboratories, New York; founded 1977
  • GIA — Gemological Institute of America; founded 1931, the most familiar name to consumers
What this means when you buy

Our advice: always confirm the stone and its report are in complete alignment before you commit.

Two labs gave different origins for the same stone. Which is right?

In this instance, we suggest seeking a third verification from a trusted third-party lab. Should the origin remain inconsistent, we would strongly urge you to avoid the acquisition."

Avoid ultrasonic cleaners
Avoid steam & sudden heat
Clean with warm water & mild soap
Store separately in a soft sleeve
05

Caring for a sapphire

Corundum is the most forgiving of the fine gemstones: at Mohs 9 with no cleavage, an untreated or simply heated sapphire stands up to daily wear and ordinary cleaning. Treated categories need more caution.
  • Warm water, mild soap, and a soft cloth are always safe
  • Avoid ultrasonic cleaning and steam in general for all sapphires
  • Store sapphires away from softer stones — corundum will scratch them
What this means when you buy

Unsure how your stone was treated? Bring it in — we will examine it for you.

Can a sapphire chip?

Hardness resists scratches, not impact. A hard knock on a girdle edge can chip any gemstone — protective settings matter for rings worn daily.

Frequently asked

Sapphire questions buyers ask us most often.

Where can I buy fine sapphires in Hong Kong?

Gem Solutions Ltd. holds a curated selection of certified sapphires in Central, Hong Kong, and sources to brief through our trade network. Browse the catalogue, or contact us with your requirements.

Is a heated sapphire a bad buy?

Not at all. Heat is the trade-accepted norm, stable for the life of the stone. The key is that it is disclosed and priced correctly — a heated stone should not be priced as an unheated one.

What makes padparadscha so expensive?

Genuine padparadscha colour is rare, in the larger size and clarity even more. The term is policed strictly by laboratories, and demand from collectors is persistent. Beware of beryllium-diffused imitator colours — the report settles it.