Red Stones Compared: Ruby, Garnet, Coral, Red Agate and Carnelian

Red is the most emotional colour in gems, and the most confusing. A Yaqoot, a garnet, a Marjan and a red Aqeeq can sit side by side in a tray and look like cousins. They are not. They differ in mineral, hardness, value and care, sometimes by a factor of a hundred in price.

First question: can you see through it?

Transparency sorts red stones quickly.

• Transparent: ruby and garnet, usually faceted.
• Translucent: carnelian and some red agate, glowing when held to light.
• Opaque: red coral, most red agate and red jasper.

Hold the stone up to a window or a phone torch. That one step narrows the field. Then look at hardness and wear: soft stones like coral show rounded, slightly scuffed edges after years of use, while ruby keeps crisp facet edges for generations.

Ruby (Yaqoot)

Ruby is red corundum, coloured by chromium, and hardness 9. The finest rubies show a strong, pure red with a slight purplish tint. Many rubies glow red under ultraviolet light because of their chromium, which is why they seem to light up in sunshine.

• Look for: fine needles called silk, small crystals, and colour that shifts slightly between red and purplish red as you turn it. That colour shift is called pleochroism.
• Treatments: heating is common and accepted. Lead-glass filled ruby is a very different product: low-grade, heavily fractured corundum with glass forced into the cracks. It is common in markets, often at prices that seem too good. Under a loupe, look for flattened gas bubbles and blue or orange flashes inside cracks. Glass-filled stones also need gentle care, because acids and jewellers' heat can damage the glass.
• Imitations: red glass, synthetic ruby and garnet-topped doublets.

See our ruby collection.

Garnet (Sang-e-Seemaq)

Most red garnets are almandine or pyrope, around 7 to 7.5 in hardness. Their red is typically deeper and darker than ruby, often leaning brownish or wine-purple.

• Look for: very even colour with no shift as you turn it. Garnet is singly refractive, so it shows no pleochroism.
• Darkness: larger garnets can look almost black indoors. Good cutting keeps them bright.
• Price: a fraction of ruby. Many old "rubies" in family jewellery turn out to be garnets, which is no shame at all.

See garnet.

Red coral (Marjan)

Coral is organic, the skeleton of tiny marine animals. It is opaque, soft at 3 to 4, and has a waxy to glassy polish.

• Look for: fine parallel growth lines, a bit like wood grain, and tiny white spots or pits on the surface.
• Imitations and treatments: dyed bamboo coral, which is more porous and often shows dye in its pits; dyed shell or bone; red glass; and plastic. Plastic feels light and warm, and its colour is often too perfect.
• Care: coral reacts with acid, so never test it with vinegar or lemon. That test damages the stone.

See red coral and our soft stone care guide.

Red agate (Surkh Aqeeq)

Red agate is banded chalcedony, hardness 6.5 to 7, usually opaque to semi-translucent.

• Look for: bands, swirls or patches of varied red, and a slightly waxy lustre.
• Treatments: many are heated or dyed to deepen colour. Very even, saturated crimson is often dyed.

See red agate.

Carnelian (Aqeeq)

Carnelian is translucent orange-red chalcedony coloured by iron. It is the same family as agate, and the line between them is partly trade naming.

• Look for: a warm, orange-leaning red that glows when held to light, with soft cloudiness rather than bands.
• Treatments: heating is very common and deepens the red.

See carnelian Aqeeq and our Aqeeq colours guide.

At a glance

What home checks cannot do

None of these clues separates a natural ruby from a synthetic one. Lab-grown ruby has the same chemistry and passes every home test. Telling natural from synthetic, or spotting glass filling reliably, needs a gemmologist and proper instruments. Our home checks guide explains where the line falls, and our how we check page explains our own process.

Tradition

In South Asian tradition, ruby is linked with the Sun and red coral with Mars, and both are often recommended by astrologers. Carnelian Aqeeq carries its own place in Muslim custom. These are traditions, and we describe them as such. Choose your stone for what it is, clearly identified, and for the red you love.