Diamonds vs Colored Gemstones: Hardness, Care and Value

Hardness is how well a stone resists scratching. Jewelers use the Mohs scale, which ranks minerals from 1 (talc) to 10 (diamond). The scale is relative, not even: diamond is far harder than corundum (ruby and sapphire), even though they sit only one step apart.

Gem	Mineral	Mohs hardness	Daily wear verdict
Diamond	Carbon	10	Best for rings and anything that takes knocks
Ruby	Corundum (red)	9	Excellent for daily wear
Sapphire	Corundum (blue and other colors)	9	Excellent for daily wear
Emerald	Beryl (green)	7.5 to 8	Hard enough, but brittle and often filled; protect it
Pearl	Organic (nacre)	2.5 to 4.5	Soft; earrings and pendants, not rings worn daily

Why it matters: household dust contains quartz, which is about 7 on the Mohs scale. Any stone softer than 7 slowly dulls from everyday contact. Diamond, ruby and sapphire are well above that line. Emerald is just above it. Pearl sits far below it, which is why pearls lose their glow when they rub against harder jewelry in a box.

A stone can resist scratches and still chip. That second property is toughness: how well a stone survives a hard hit. Diamond is the hardest gem but it has cleavage planes, directions along which a sharp blow can split it. Ruby and sapphire have no cleavage and are very tough. Emerald is the weak one: it usually has internal fractures, and a knock in the wrong spot can crack it.

• Diamond: top scratch resistance; protect pointed tips (pear, marquise, princess corners) with prongs or a V-tip.
• Ruby and sapphire: the most forgiving colored stones for rings and bracelets.
• Emerald: best in earrings and pendants, or in a protective setting if worn as a ring.

Setting style helps. A bezel or halo shields the edge of a stone. Read prong vs bezel setting before choosing an everyday colored-stone ring.

Most colored gemstones on the market are treated in some way. That is normal. What is not acceptable is hiding it. The FTC Jewelry Guides (16 CFR Part 23) say it is deceptive to fail to disclose a gemstone treatment that is not permanent, that creates special care needs, or that significantly affects the stone's value.

Gem	Common treatment	What it means for you
Ruby, sapphire	Heating	Very common and stable. Improves color and clarity.
Ruby	Glass filling of fractures	Lower value; sensitive to heat and chemicals. Must be disclosed.
Emerald	Oil or resin in fractures	Very common. Avoid ultrasonic and steam cleaners.
Pearl	Bleaching, dyeing	Color may change over time with harsh chemicals.
Diamond	Clarity enhancement, color treatment	Uncommon in fine jewelry; must be disclosed under the same rule.

The FTC Guides also cover lab-created stones. A lab-grown ruby or sapphire is the same mineral as a mined one, and a seller must say clearly that it is laboratory-created. The same rule applies to diamonds: lab-grown must be disclosed, and words like "natural" or "genuine" cannot be used alone to describe them. Our guide to lab diamonds explains how that disclosure looks in practice.

Diamonds are priced on the 4Cs, with color graded on a D to Z scale where less color is better. Colored stones flip that logic. For rubies, sapphires and emeralds, the color itself is the main value driver.

1. Color: a strong, even, saturated hue is worth the most. Too dark or too pale lowers value.
2. Clarity: expected standards differ by gem. Emeralds almost always show inclusions, often called "jardin." Sapphires are expected to be cleaner.
3. Treatment: untreated stones of the same look sell for more than treated ones.
4. Size: large fine rubies and emeralds are rarer than large diamonds of similar quality.
5. Origin: some sources command a premium, but origin claims need a lab report to back them.

Most colored stones in fashion jewelry are small accents, so the value of the piece rests mostly on the gold and the diamonds around them. That is how our gemstone pieces are built: colored centers or accents set with round brilliant diamonds in 14K gold.

One more value point: a lab-created ruby or sapphire has the same hardness and look as a mined one but sells for a small fraction of the price, much like lab-grown diamonds. Neither is a lesser stone for wear. They are simply priced on supply. If a colored stone seems cheap for its size and color, ask first whether it is lab-created, then whether it is treated. Both answers change what it is worth.

Pairing a colored center with a diamond halo or diamond accents gives you color plus sparkle, and the diamonds protect the edges of the colored stone. Real examples from our catalog, all 14K and available in yellow, white or rose gold:

Piece	Colored stone	Price
Princess Blue Sapphire Hoops	Princess-cut blue sapphires with diamonds	$1,280
Charlotte Blue Sapphire Huggies	Round blue sapphires with diamonds	$1,600
Alysa Blue Sapphire Bracelet	Oval blue sapphires with diamonds	$2,395
Ruby Teardrop Ring	Pear-cut ruby, diamond halo	$785
Esme Ruby Bracelet	Round rubies with diamonds	$3,535
Oval Emerald Ring	Oval emerald, diamond halo	$835
Emerald Constance Earrings	Oval emeralds with diamonds	$730
Royal Pearl Earrings	Freshwater pearls with a diamond cluster	$4,115

A simple rule for mixing: put the harder stone where the knocks land. Sapphire and ruby work on rings and bracelets. Emerald and pearl are happiest on ears and necks. See the full range in gemstone jewelry, gemstone earrings and gemstone rings.

Warm water, a drop of mild dish soap and a soft toothbrush are safe for almost everything. GIA recommends that method for most gems. The risk comes from machines and chemicals.

Stone	Soap and soft brush	Ultrasonic cleaner	Steam
Diamond (untreated)	Yes	Usually safe if stones are secure	Usually safe
Ruby, sapphire (heated only)	Yes	Usually safe	Usually safe
Glass-filled ruby	Yes, gently	No	No
Emerald	Yes, gently, no soaking	No	No
Pearl	Damp soft cloth only	No	No

Two more habits keep colored stones looking new. Put pearls on last, after perfume and lotion, because cosmetics eat at the surface. And store each piece separately, so a diamond never rubs against a softer stone. For diamond-only pieces, follow how to clean diamond jewelry.

Heat is the other quiet danger. Filled emeralds and glass-filled rubies can be damaged by a jeweler's torch, so any work on a colored-stone piece should start with the jeweler knowing exactly which stone and treatment is in it. Keep the original receipt or listing that names the stone; it is the easiest way to pass that information on.

Three very different things can look alike across a jewelry counter. Knowing the words keeps you from paying natural-stone prices for something else.

Term	What it is	Example
Natural	Formed in the earth, mined	Mined sapphire, mined diamond
Lab-created (lab-grown)	Same chemistry and crystal as the natural stone, grown in a factory	Lab-grown diamond, lab-created ruby
Simulant or imitation	A different material made to look like the real stone	Cubic zirconia or glass passed off as diamond; dyed glass as emerald

Lab-created stones are real gems. A lab-grown diamond is diamond and tests as diamond. A lab-created sapphire is corundum, with the same hardness of 9. They simply cost less than mined stones of the same look, and the seller must say they are lab-created.

Simulants are a different story. Cubic zirconia, for example, sits around 8 to 8.5 on the Mohs scale and scratches and clouds with time. If a "diamond" piece costs far less than gold-and-diamond math allows, it is probably a simulant. Our guide to spotting fake diamonds walks through the checks.

Before you pay for any piece with a ruby, sapphire, emerald or pearl, get these five answers in writing:

1. The species. "Blue sapphire," not just "blue stone."
2. Natural, lab-created or imitation. All three exist at every price point.
3. Any treatment. Heated, oiled, filled, dyed or none.
4. The metal and karat. A colored stone in 14K gold is a fine piece. The same stone in plated brass is costume jewelry.
5. The diamonds. If the piece has diamond accents, the total carat weight and whether they are natural or lab-grown.

A seller who answers all five without hesitation is a seller who knows their stock. A seller who dodges any of them is telling you something too.

Pick a diamond when the piece will be worn every day on the hand or wrist, when you want maximum sparkle, or when you want a stone that ignores scratches for decades. Browse diamond jewelry for the full range.

Pick a sapphire or ruby when you want color on a ring or bracelet and still need toughness. Pick an emerald or pearl for earrings, pendants and occasion pieces, where the stone sees fewer knocks.

Whatever you choose, ask for the stone type, any treatment and the metal karat in writing. If you want to compare a sapphire, ruby, emerald and diamond in the same light, the Miami showroom has them side by side. Find directions on the showroom page.