Ruby vs Spinel: Color, Value, Hardness & How to Choose

Throughout history, some of the most famous “rubies” in the world turned out to be spinels. The Black Prince’s Ruby in the British Crown Jewels. The Timur Ruby once belonging to Mughal emperors. Both are red spinels. For centuries, gemologists lacked the tools to distinguish them — today, you can tell them apart in seconds with the right knowledge.

Ruby and red spinel are not the same stone. They come from different mineral species, have different physical properties, and occupy very different positions in the market. Understanding the distinction helps you choose the right stone for your purpose — and avoid paying ruby prices for a spinel, or missing a high-quality spinel while chasing ruby.

Ruby vs Spinel: Quick Comparison

Property	Ruby	Red Spinel
Mineral species	Corundum (Al₂O₃)	Spinel (MgAl₂O₄)
Hardness (Mohs)	9	8
Color range	Red to pinkish-red	Red, orange-red, pink-red, vivid red
Cause of color	Chromium	Chromium
Price per carat (fine, 1ct)	$800–$5,000+	$200–$1,500+
Common treatment	Heat, lead glass filling	Usually untreated
Best certification	GRS, GIA, Gübelin	GRS, SSEF
UV fluorescence	Strong red	Weak to moderate

Color: Similar at First Glance, Different in Detail

Both ruby and red spinel owe their color to chromium, which is why they look so similar. Ruby tends toward a slightly purplish-red to pure red, with strong red fluorescence under UV light that gives top-quality Burmese rubies their coveted “pigeon blood” glow. Red spinel typically shows a cleaner, purer red without the purplish secondary hue found in many rubies. High-quality red spinels from Burma’s Mogok Valley display a vivid, slightly orange-tinged red that many experts consider more attractive than commercial ruby — without the treatment concerns that affect most rubies in the market.

Value and Investment

Ruby is one of the three “precious” gemstone categories alongside sapphire and emerald, and fine natural rubies command among the highest per-carat prices of any colored gemstone. A 1-carat “pigeon blood” Burmese ruby certified by GRS can fetch $3,000–$8,000 per carat at retail.

Red spinel has been significantly undervalued for most of its history (partly because it was confused with ruby), but collector demand has increased substantially since the 2010s. A 1-carat GRS-certified red spinel from Burma with vivid color sells for $400–$1,500 per carat — excellent value for a genuinely beautiful, naturally unheated stone.

Treatment: A Critical Difference

The vast majority of rubies on the market are heat-treated, often heavily. Lead glass filling (fracture filling) is common in commercial ruby and significantly reduces value. A natural, unheated ruby with good color is exceptionally rare and commands a large premium.

Most high-quality spinels are naturally untreated. When you buy a certified red spinel, you are almost always buying an untreated stone. This means a fine red spinel often represents better value per dollar than a treated ruby of similar appearance.

How to Choose: Ruby or Spinel?

Choose ruby if: Investment or resale is the primary driver, you want the most recognized precious gemstone category, you can find a natural unheated specimen with certification, or you are targeting Burmese “pigeon blood” specifically.

Choose red spinel if: You want a beautiful, vibrant red stone at better value, natural untreated provenance is important to you, you appreciate rarity in the collector sense (fine spinel is genuinely hard to find), or you are a jewelry designer seeking a durable (Mohs 8) red stone.

Shop Ruby and Red Spinel at MYGEMSET

Both categories are available with full certification and 4K macro video. All ruby and spinel sold at MYGEMSET is accompanied by certificates from recognized independent laboratories with explicit treatment disclosure. Browse our certified natural rubies and certified natural spinels — all with same-week worldwide shipping.

Ruby vs Spinel: Color, Value & How to Tell the Difference