Last updated on April 17, 2023
At first glance, garnet and ruby look very similar to an untrained eye. Although both have a vibrant red colour, one is a precious gemstone, while the other is a semi-precious gem. Garnet vs ruby – let’s discover the difference and learn not to confuse the two.
Garnet vs Ruby Formation
Before technological advancement, all red gemstones were considered rubies, including garnet. Both are red and sparkly, so no one wondered why the difference even mattered.
Today, the difference matters because ruby is one of the four precious gemstones, along with diamond, emerald and sapphire, and garnet is a somewhat abundant semi-precious gem. Both stones have some benefits to offer, but the actual value of rubies is significantly higher.
Garnet refers to a large group of silicate minerals, that share a similar crystal structure and physical properties but vary in chemical composition. With different varieties and chemical formulas, garnets can be formed in many ways. However, in general, garnet crystals form when sedimentary rocks get subjected to immense pressure and temperature. Such conditions melt the rock, and as it cools, it crystallizes in cracks and gaps in metamorphic rock surroundings. Once silicate material mixes with other chemical impurities, it creates various garnet colours.
Rubies, on the other hand, are formed from corundum crystals that have been exposed to trace amounts of chromium. These crystals are typically formed within metamorphic rocks under extreme heat and pressure over millions of years.
In terms of their chemical composition, garnets are a group of silicate minerals that contain various elements, such as iron, magnesium, and calcium. The exact chemical makeup of a garnet crystal depends on its specific type and the conditions under which it is formed. Rubies, on the other hand, are a type of mineral called corundum, which is made up of aluminum oxide (Al2O3) with trace amounts of chromium.
Garnet vs Ruby Colour and Light
Both ruby and garnet have deep red colours. However, there are several distinctions in their colour, hue and intensity, which help us set garnet and ruby apart.
Ruby gets its red colour from the presence of chromium microelements, while garnet is coloured red by iron during its formation process. This difference causes rubies to have a more intense shade of red. In comparison, garnet appears slightly lighter and paler. In addition, ruby has a cooler red undertone and sometimes appears purplish or bluish, while garnet has a warmer hue and leans towards an orang-yellowish shade.
It is also worth mentioning that ruby comes in red colour only, while garnet is usually red, however; it can be pink, purple, brown, yellow, orange, green, black and colour-change, which appears blue in daylight and red or purple under artificial light.
Another way to determine whether you are looking at a garnet or a ruby is the way the gem reflects light. If the gemstone reflects a rainbow of colours, including green and yellow, most likely you are looking at a garnet, as ruby absorbs green and yellow due to its chemical makeup.
Garnet vs Ruby Clarity and Durability
Rubies typically display inclusions, which are not looked upon as negative attributes as they would be for diamonds, for example. On the opposite, these flaws are considered part of the character of rubies. Garnets, on the other hand, are typically eye-clean. Blemishes and inclusions in garnets are not tolerated.
Ruby is a very durable gemstone, with a rank of 9 out of 10 on the Mohs scale. Garnet is a considerably less durable gem, with a rank of 6.5 – 7.5 on the Mohs hardness scale, meaning it is a softer gemstone in comparison. Although you might not be able to determine the hardness of the stone by looking at it, the difference in durability is quite an important factor that can help a professional tell between the two.
Garnet vs Ruby Properties
|Chemical Name||Silicate||Aluminium oxide|
|Colours||Typically red, but can be orange, green, yellow, purple, black, or brown||Red|
|Hardness||6.5 - 7.5 on the Mohs scale||9 on the Mohs scale|
|Refractive Index||1.72 - 1.94||1.76 - 1.78|
|Specific Gravity||3.5 - 4.3||4.0 - 4.1|
|Transparency||Transparent to translucent||Transparent to opaque|
|Lustre||Vitreous to resinous||Vitreous|
|Fluorescence||Variable||Strong - carmine red|
Featured image: garnet - STUDIO492 / Shutterstock, ruby - STUDIO492 / Shutterstock. A derivative work by Diamond Buzz.