Ownership, care & collecting

The first check is the seller. Established jewelers and dealers can supply references, often belong to trade organizations with codes of conduct, and put a full description of the stone, including any treatment, on the invoice. GIA's buying guide advises working with trained staff, such as holders of its Graduate Gemologist or Applied Jewelry Professional credentials, and asking for a grading report.

A laboratory report, often called a certificate, describes a stone as examined; it is not a valuation. For a diamond, check that the report number matches any laser inscription on the girdle and confirm the report online, for example through GIA's Report Check service. For a colored stone, the report should state whether treatment was detected and, where it matters to price, give a recognized laboratory's opinion of geographic origin. Laboratories differ in strictness, so price comparisons are most meaningful between stones graded by the same lab.

In the United States, the Federal Trade Commission's Guides for the Jewelry, Precious Metals, and Pewter Industries (16 CFR Part 23) make it deceptive not to disclose a gemstone treatment that is not permanent, that creates special care requirements, or that significantly affects the stone's value. For online purchases, GIA recommends buying stones with reports from reputable laboratories, studying 360° views and confirming the return policy before paying. A written return period also gives the buyer time to have the stone checked by an independent gemologist or appraiser.

How a stone survives daily wear depends on three separate properties. Hardness is resistance to scratching, toughness is resistance to chipping and breaking, and stability is resistance to heat, light and chemicals. Topaz rates 8 on the Mohs scale but has a cleavage, a plane along which it can split, so a sharp knock may break it. Jade rates only about 6–7 yet is exceptionally tough. Pearl and amber are soft, and pearls are damaged by acids in perfume, cosmetics and perspiration.

Ultrasonic cleaners loosen dirt with high-frequency vibration, and steam cleaners blast it away with hot pressurized steam. Both can widen fractures, split stones along cleavage, drive out the oils or resins used as fillers and shock heat-sensitive gems. GIA's gem-by-gem guidance, summarized in the table below, treats warm soapy water and a soft brush as the safe method for nearly all gems. It describes both machines as safe for untreated or heat-treated ruby and sapphire and advises against them for emerald, opal, pearl, tanzanite, turquoise and moonstone, among others. For diamonds, GIA advises against ultrasonic and steam cleaning at home because vibration can loosen stones in their settings, and notes that jewelers inspect pieces first.

Store jewels separately in soft pouches or divided boxes, because diamond and corundum scratch softer gems and metals. Remove rings for heavy manual work, and have prongs checked periodically, since a worn setting can release a stone.

Standard homeowners and renters policies in the United States usually cap jewelry theft coverage at a low amount, which the jewelry insurer Jewelers Mutual puts at US$1,000–2,500. Owners of valuable pieces therefore buy a separate jewelry policy or list items individually on a policy endorsement, which can extend cover to loss and damage as well as theft, depending on the terms.

The insured amount usually comes from an insurance appraisal, which estimates retail replacement value: what it would cost to buy or make a comparable piece new. That figure is normally well above what the owner could get by selling. A useful appraisal names the appraiser and their qualifications, describes each stone and the metal with measurements, weights, grades and treatments, refers to any laboratory reports, and includes photographs. Because gem and metal prices move, Jewelers Mutual recommends a new appraisal every two years to avoid being underinsured. Insurers generally need an appraisal or equivalent proof of value when a claim is made, even if none was required when the policy began.

Keep a file for each important piece: purchase invoice, laboratory reports, appraisals, photographs from several angles and repair receipts. Store copies away from the jewelry itself, for example with a bank, a lawyer or a secure online service, so the records survive the same fire or burglary.

Selling a gem is slower than buying one, and sellers rarely recover the purchase price. Retail prices carry the margins of several intermediaries, so an owner receives well below the replacement value on an insurance appraisal.

A buyback or trade-in is offered by some retailers for pieces they sold. Kay and Zales credit the full original purchase price, but only against a new piece costing at least twice as much, and only for diamond jewelry bought from the same chain. Selling outright to a dealer is quicker, and the offer builds in the buyer's resale margin and risk: in the Bain and AWDC value chain for 2010, loose polished diamonds changed hands at about 30% of what consumers paid for diamond jewelry.

On consignment, a dealer displays the piece and pays the owner an agreed amount only if it sells. The owner keeps title until then, so a written agreement should set the minimum price, commission, duration, insurance and return of unsold goods.

Auction suits important, well-documented stones. The house sets an estimate and often a reserve, a confidential minimum, charges the seller a commission and adds a buyer's premium, 28% on the first US$2 million at Christie's and Sotheby's in 2026.

A pawn loan is secured by the item. The UK regulator found that British pawnbrokers lend about 50% of their own valuation, and they keep and sell the item if the owner does not repay with interest.

Gems are easy to overlook in an estate and easy to argue over. A written inventory with photographs, laboratory reports and recent appraisals tells executors what exists and where it is kept, and specific bequests in a will, naming which piece goes to which person, reduce disputes over jewels that look alike. Heirs also need to know where documents and safe-deposit keys are.

Tax valuations use a different standard from insurance. In the United States, IRS Publication 561 defines fair market value as the price at which property would change hands between a willing buyer and a willing seller, neither being forced to act and both knowing the relevant facts. It notes that gems and jewelry require specialist appraisers who consider cut, color, weight, flaws and current fashion, that sentimental value does not count, and that a famous former owner may add value. Donations of property valued above US$5,000 require a qualified appraisal. When gems are later sold at a gain, US federal law treats them as collectibles, taxed at a maximum 28% rate on long-term gains.

Other countries set their own rules. In the United Kingdom, as of 2026, inheritance tax is charged at 40% on the part of an estate above the £325,000 nil-rate band, and gifts made within seven years before death can still be taxed. Owners of valuable collections usually plan with a lawyer or tax adviser and a qualified appraiser together.

Collectors pursue gems for rarity, beauty or completeness rather than for wear. Some try to assemble every gem species, including collector stones such as benitoite, painite, grandidierite and taaffeite, which usually come in small sizes and often need laboratory testing to identify with confidence. Others collect one species in every color, or stones from classic localities. Because rare species trade infrequently, prices are hard to confirm and resale can take time.

Pairs and suites add the problem of matching. A pair for earrings must agree in color, tone, size, cut and clarity, and a suite of several stones for a necklace or a parure (a matched set of jewels such as necklace, earrings and bracelet) multiplies that difficulty. Well-matched groups are hard to assemble and are usually priced accordingly.

Mineral specimens and cut stones form overlapping but distinct markets. A specimen is valued as an intact natural crystal, often still attached to its host rock (the matrix), for its shape, luster, color, locality and overall look. Cutting a fine specimen destroys that value even if the gem inside is clean.

Finally, a provenance file, the documented chain of ownership, protects both value and title. It should hold invoices, laboratory reports, earlier auction catalogs, photographs, import and export papers and correspondence. For historic or royal pieces, documented ownership can raise auction prices well above those of comparable stones without it.