What Sets a Gem's Price? Why Two Stones of the Same Weight Differ

People often ask us why one 5 ct sapphire costs a few thousand rupees and another costs several lakh. Weight is the same. The name is the same. The difference lies in a handful of qualities that the trade has priced for centuries. Here they are, in roughly the order that matters.

Per-carat pricing

Gems are priced per carat, not per stone. A dealer will say "this Neelam is so many rupees per carat", and the total is that rate multiplied by the weight. That makes it easier to compare stones of different sizes. In Pakistan you will also hear prices per ratti; our ratti guide explains the conversion and why you should always ask which ratti is meant.

The key point: the per-carat rate itself changes with quality and size. A better stone does not just cost more in total. It costs more per carat too.

Colour

For coloured gems, colour is usually the single largest factor. Buyers pay most for:

• A pure hue without grey, brown or unwanted tints.
• A medium to medium-dark tone, neither washed out nor inky.
• Strong saturation that looks vivid in ordinary room light.
• Even colour without obvious zoning seen from the top.

A small step in colour can mean a large step in price. That is why photos and honest description matter so much. Our Neelam guide explains colour in more depth.

Size jumps

Larger stones of good quality are rarer, so the per-carat rate rises with size. It does not rise smoothly. It tends to jump at familiar thresholds.

• Around 1 ct, 2 ct, 3 ct and 5 ct, prices often step up, because many buyers look for those numbers.
• In Pakistan, round ratti figures behave the same way. A stone just over 5 ratti can carry a premium over one at 4.9.
• Above roughly 5 ct, fine sapphire and ruby become genuinely scarce, and rates climb steeply.

A practical tip: a stone just below a threshold can look almost identical on the hand and cost noticeably less.

Clarity

Most coloured gems contain inclusions. That is normal. What matters is whether they affect beauty or durability. Small inclusions you cannot see without a loupe have little effect on price. Large cracks, cloudiness that dulls the colour, or anything that reaches the surface and risks breakage will lower it. Emerald is judged more gently on clarity than sapphire, because clean emeralds are so rare.

Cut

Cutting can make or break a stone. A good cut returns light evenly and shows the colour at its best. A poor one leaves a dull window in the centre or dark patches. Many stones are cut for weight rather than beauty, with a deep, bulging belly underneath. Such a stone weighs more but looks no larger from the top, so you pay for hidden carats.

Origin

Certain origins carry a premium because of history and reputation, such as Kashmir or Sri Lanka for sapphire, or Burma for ruby. That premium is real in the trade, but it should rest on a credible lab's origin opinion, and it should never replace your own eye. A fine stone from Madagascar or East Africa can outshine a poor one with a famous label. We list origin only where we have it.

Treatment

Treatment status has a large effect on price.

• Untreated stones with fine colour are the rarest and cost the most, often far more than heated equivalents.
• Heated stones are standard in sapphire and ruby and form most of the market.
• Deeper treatments such as diffusion, glass filling or dyeing reduce value considerably and must be disclosed.

On our pages, treatment status is shown as recorded. Where a stone has not been lab-tested for treatment, we say so, and you are welcome to have it tested. See how we check.

Rarity and demand

Some prices reflect rarity in nature. Others reflect demand. In Pakistan, astrological demand keeps blue and yellow sapphire, ruby and red coral in steady demand, which supports their prices. Fashion plays a part too. Stones like tanzanite or Ethiopian opal can rise or fall as supply changes.

Two stones, same weight

Here is how it plays out. Imagine two blue sapphires, each 4.50 ct.

Both are natural sapphire. Both weigh the same. Stone B may cost many times more per carat, and fairly so.

Using this when you shop

• Decide what matters to you first: colour, size or budget.
• Compare per-carat rates, not totals.
• Consider stones just under the size thresholds.
• Ask about treatment, and value disclosure over a famous name.

Our price list shows typical ranges for each gem. You can compare collections such as blue sapphire, ruby, yellow sapphire and emerald side by side.