Buying Fine Jewelry: Gold Karats, Diamonds and What Labels Mean

Fine jewelry is one of the few purchases where a single word on a tag can mean a difference of hundreds or thousands of dollars. "Gold," "gold-tone," "gold-plated" and "solid 14K gold" all describe very different things. In the United States, the Federal Trade Commission's Guides for the Jewelry, Precious Metals, and Pewter Industries, usually called the Jewelry Guides, set out what sellers may claim. Knowing the basics turns a confusing counter into a straightforward comparison.

Gold: what the karat number means

Pure gold is 24 karats, which is too soft for most jewelry. It is mixed with other metals (alloys) for strength and color. The karat number tells you how many parts out of 24 are gold.

Under the FTC guides, an item should not be described simply as "gold" in the US unless it is at least 10 karats. Below that, it is not marketed as karat gold.

Color comes from the alloy. Yellow gold keeps a warm tone; white gold is alloyed with whiter metals and usually plated with rhodium, which can wear and need replating over time; rose gold gets its pink tone from copper.

Plated, vermeil, gold-filled: the gold that is not solid

Many beautiful, affordable pieces are not solid gold. That is fine, as long as you know what you are paying for.

• Gold-plated (or gold electroplate): a thin layer of gold over a base metal such as brass. It can wear through, especially on rings and bracelets.
• Gold vermeil: under the FTC guides, sterling silver coated with gold of at least 10 karats and a minimum thickness. Better than standard plating, but still a coating.
• Gold-filled: a thicker layer of karat gold mechanically bonded to a base metal, making up a set minimum proportion of the item's weight. Much more durable than plating; often used for chains and earrings.
• Gold-tone: a gold color with no stated gold content at all.

If a piece is labeled with a karat mark, the US National Gold and Silver Stamping Act also governs how accurate that mark must be. When in doubt, ask the seller to put "solid 14K gold" (or whatever they are claiming) on the receipt.

Silver and platinum

• Sterling silver must be 92.5% silver, often stamped "925." It tarnishes, but polishes back easily.
• Platinum in US jewelry is typically 95% pure and stamped "PLAT" or "950 Plat." It is dense, naturally white and does not need rhodium plating, but it scratches into a soft matte patina rather than losing metal.

Diamonds: the 4Cs

The 4Cs system, popularized by the Gemological Institute of America (GIA), describes the characteristics that drive a diamond's price.

• Cut refers to how well a diamond's proportions, symmetry and polish return light. For round brilliants it is graded from Excellent down to Poor. Cut has the biggest effect on sparkle, so it is rarely the place to economize.
• Color is graded on a D (colorless) to Z (light yellow or brown) scale. Differences between neighboring grades are hard to see once a stone is set, especially in yellow or rose gold.
• Clarity measures internal "inclusions" and surface "blemishes," from Flawless down to Included. Many stones in the middle of the scale look clean to the naked eye, which is what matters day to day.
• Carat is weight, not size. Two stones of the same weight can look different sizes depending on cut proportions.

A practical approach for many buyers: prioritize a strong cut, choose color and clarity grades that look clean and bright to your own eye in the intended setting, and let carat be whatever the budget allows.

Natural, lab-grown and simulants

Since 2018, the FTC's guides have defined a diamond by its properties rather than its origin, which means laboratory-grown diamonds are diamonds. What the rules require is clear disclosure: a seller must describe them with terms such as "laboratory-grown," "laboratory-created" or "[manufacturer name]-created," and must not describe them as natural.

Simulants are different. Cubic zirconia and moissanite may look similar but are different materials, and must not be called diamonds.

Lab-grown diamonds generally cost significantly less than natural diamonds of similar appearance, and their secondhand value is typically low. Natural diamonds also lose a large share of their retail price on resale. Neither should be bought as a financial investment.

Grading reports and certificates

For any significant diamond purchase, ask for an independent grading report from a recognized laboratory. Check that:

• The report number matches the inscription on the stone's girdle, if it has one (a jeweler can show you under magnification).
• The carat weight, measurements and grades match the seller's description.
• The report states clearly whether the stone is natural or laboratory-grown.

A store's own "appraisal" is not the same as an independent grade. Appraisals for insurance purposes often list a replacement value higher than what you paid, which is not evidence of a bargain.

Colored gemstones and pearls

Many colored stones are routinely treated, for example by heating, to improve color. Under the FTC guides, sellers should disclose treatments that are not permanent, that require special care, or that significantly affect value. Ask directly: "Has this stone been treated, and how?"

Pearls are described as natural, cultured or imitation. Nearly all pearls sold today are cultured, which is a legitimate, real pearl grown with human help; "imitation" means a manufactured bead.

Caring for fine jewelry

Good jewelry lasts generations, but it still needs attention.

• Store pieces separately. Diamonds can scratch other stones and metals, and chains tangle. Soft pouches or a lined box with compartments solve both problems.
• Put jewelry on last and take it off first. Lotions, perfume, hairspray and chlorine dull metals and can damage pearls and porous stones.
• Remove rings for heavy work, the gym, gardening and cleaning with chemicals.
• Clean gently. Warm water, mild soap and a soft brush suit most gold and diamond pieces; pearls and many colored stones need only a soft, damp cloth.
• Have prongs checked. A jeweler can inspect settings for wear, often for free or a small fee, once or twice a year. A loose prong is the most common way a stone is lost.

Shopping checklist

1. Decide on metal and karat based on how often you will wear the piece.
2. Ask for the exact description, including karat, plating or treatment, in writing.
3. For diamonds, request an independent grading report and check it against the stone.
4. Understand the return policy, resizing policy and warranty before paying.
5. Pay by credit card for dispute protection, and keep every receipt and report.
6. Insure significant pieces, either under a homeowner's or renter's policy rider or a specialist jewelry policy.

Jewelry is often bought for a moment and kept for a lifetime. Spending ten minutes on the label means the story attached to it is the one you meant to buy.