Vintage gemstone jewellery has a way of drawing you in. Perhaps it is the soft glow of a well-worn cabochon, or the way older settings seat a stone closer to the skin than modern pieces. Whatever the reason, if you collect or inherit such pieces, you will quickly want to know what you are actually holding. Gem testing laboratories exist for a reason, but a great deal can be learned at the kitchen table with good light, a loupe, and a little patience.

Start by Looking, Not by Testing

Before you reach for any tool, clean the piece gently. Old soap residue, skin oils and tarnish hide the very details you are trying to read. Use lukewarm water with a drop of mild washing-up liquid and a soft baby toothbrush, then dry with a lint-free cloth. Work near a window in daylight, never under a single warm bulb, which flatters colour and disguises flaws.

A ten-times jeweller's loupe and a small torch are enough for most of the work. Look at the stone against a neutral background, then with the torch behind it, then again under reflected light to catch scratches and wear. Keep a notebook. Comparisons between pieces teach you far more than studying one stone in isolation.

Jade: Colour, Lustre and Surprising Heft

Jade appears in vintage jewellery as carved panels, beads, bangles and cabochons, usually in green, but also lavender, grey, cream and near-black. The first clue is lustre. Old jade has a soft, soapy, almost waxy shine. If a stone gleams like glass, be suspicious of paste, resin or a polished substitute.

The second clue is weight. Jadeite is remarkably dense — noticeably heavier in the hand than a piece of glass or quartz of the same size. Even a modest cabochon should feel as though it has a leaden core. Third is surface character. Genuine old jade develops a gentle patina on high points of the carving, where decades of handling have polished it smooth. The recesses stay slightly duller. That contrast is very difficult to fake, and dyed jade often shows colour pooling in fine surface cracks, which the loupe will reveal.

Amethyst: Colour Zoning and the Fading Question

Amethyst is quartz coloured purple by iron, and it has a few habits you can learn to read. Under a loupe, much amethyst shows colour zoning — patches or angular bands of deeper purple fading into colourless or milky areas. Look for colour concentrated toward one end of the stone.

Many older amethysts look paler than you expect. This is entirely normal. Amethyst fades in prolonged sunlight, and a brooch that spent forty summers on a windowsill will have lost noticeable colour. Crisp facet edges are also a good sign. Quartz sits at seven on the Mohs scale, so a genuine stone keeps sharp junctions between facets even after a century. Glass imitations, being softer, show rounded or slightly ragged facet edges, and often contain round gas bubbles under magnification. Be cautious with stones that are strongly pink rather than purple; these may be heat-treated material or, quite often, nothing to do with amethyst at all.

Garnet: Deep Reds and Honest Density

Garnet is a family rather than a single stone. Victorian and Edwardian jewellery most often uses almandine, a brownish, slightly gloomy red, or the brighter Bohemian pyrope, sometimes set in rose gold as a foil to its colour. Green garnets such as tsavorite and demantoid appear in finer later pieces.

Garnets feel heavier than quartz and have a rich, resinous glow rather than a watery sparkle. They are singly refractive, so a red stone that shows clear doubling of its back facets under the loupe is almost certainly not garnet. Inclusions help too: almandine often contains angular crystals and fine rutile needles, while demantoid is famous for curved, horsetail-like fibres. A red stone that looks entirely clean, unusually brilliant and suspiciously light in the hand deserves a second opinion.

Surface Wear: The Oldest Signature of All

Wear is one of the most honest clues in vintage jewellery, because it is hard to reproduce convincingly. Turn the piece in reflected light and look at the edges of facets, the rim of a cabochon and the contact points with the setting. Genuine age brings minute chips and a slightly nibbled silhouette. Check the metal as well. Claws wear thin, solder lines darken, and settings loosen. Paste stones, being soft, often show dull scuffed facets that no amount of cleaning will restore.

Caring for Older Stones

Care is mostly about restraint. Warm water, mild soap, a soft brush and a gentle dry is right for jade, amethyst and garnet. Avoid vinegar, lemon juice and abrasive polishes, which attack both metal and stone. Ultrasonic cleaners are best avoided for jade, opal, emerald, pearl and any stone that may be fracture-filled, as vibration can worsen existing damage.

• Store pieces separately in soft pouches to prevent stones scratching one another.
• Keep amethyst out of direct sunlight and away from sunny windowsills.
• Remove rings before gardening, washing up or swimming in chlorinated water.
• Have settings checked once a year, especially on older claw-set pieces.
• Wipe stones with a soft cloth after wearing to remove skin oils.

Handle your vintage pieces often, but handle them thoughtfully. Every scratch and soft edge tells you something about where a stone has been, and with a loupe, good light and a careful hand, you will soon find that older jewellery reveals its secrets willingly.