What Is the Black Stone in a Black Pendant Necklace?
Summary
The word black names a color. The stone behind it may be onyx, spinel, black diamond, enamel, glass, ceramic, or something else. If the listing never names it, you have nothing to compare price, durability, or care against.
Of the three gems, onyx is the softest. Spinel is harder and looks closer to black diamond. Many black diamonds sold in jewelry were treated to turn black.
After the stone, check the pendant dimensions, metal, bail size, chain strength, and whether the pendant comes off. A black stone draws the eye, so the chain and setting need to look and feel in proportion.
First, identify the black material
A black oval in a product photo can be onyx, glass, enamel, spinel, treated diamond, or something else, each with its own hardness, value, and care.
The FTC’s guidance for jewelry advertisers says sellers should not use the unqualified name of a precious or semi-precious stone “to describe any product that is not in fact a mined stone of the type described.” A pendant sold as black spinel or onyx should contain that stone, not something of the same color.
If the listing says only “black stone,” ask what it is before you compare its price with a pendant that names the gem.
Onyx gives a smooth, even black
GIA’s black diamond buying guide describes onyx as having “a softer, matte to semi-gloss finish.” It puts onyx at “around 6.5 to 7 on the Mohs scale,” which makes it “more prone to scratches and wear over time.”
A pendant takes fewer knocks than a ring. In a drawer, keep it away from diamond and spinel pieces, which can scratch it.
Black spinel is harder and closer to diamond
GIA’s care guide says “Spinel ranks 8 on the Mohs scale and has good toughness, making it a durable gem for jewelry.” The same guide warns that “the Mohs scale is deceptive. The steps between the minerals are not evenly spaced.” The black diamond guide describes black spinel as the natural gem that “more closely mimics the appearance of black diamond.”
If the seller says natural spinel and the price is significant, GIA’s buyer’s guide has two suggestions: consider a report from an independent laboratory, and “Make sure your invoice specifies that the spinel you are buying is natural.”
Ask whether a black diamond was treated
According to GIA, most natural black diamonds get their color from countless tiny mineral inclusions, such as graphite, pyrite, or hematite, and from small internal fractures that stain black over time. Those fractures make it “more brittle and prone to chipping or breaking if struck sharply.”
GIA also notes that “Many black diamonds used in jewelry and engagement rings today have been treated to achieve their dark color.” The methods it names are high-temperature annealing and irradiation. Ask which kind you are buying. For a higher-value stone, a GIA Colored Diamond Identification and Origin Report “can confirm whether the diamond’s color is natural or the result of treatment.”
For black diamonds, GIA writes, the evenness of the color and the quality of the cut “typically have a greater impact on value than size,” which makes carat weight “a secondary consideration.” To see how large the pendant will look, compare the millimeter dimensions. For cleaning, the guide says to skip ultrasonic and steam methods and use mild soap and water.
Metal and chain change the look
Yellow and rose gold give a warm contrast with black; white metals give a cooler look. Either way, the listing should name the metal.
If the pendant is plated or mixed-material, check the bail and chain separately. A heavy-looking pendant on a thread-thin chain looks out of balance even if the chain holds it.
Check the bail before planning to swap chains
To move the pendant to another chain, that chain’s clasp has to pass through the bail.
Look for the bail opening in the listing. If it is 3 mm and the clasp on your other chain is 4 mm across, the pendant stays on the chain it came with.
Looking for a piece? Browse necklaces in the feed →
Sources
- GIA 4Cs, Black Diamond Buying Guide: What You Need to Know
- GIA, Spinel Buyer’s Guide
- GIA, Spinel Care and Cleaning Guide
- Federal Trade Commission, In the Loupe: Advertising Diamond, Gemstones and Pearls
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