Prehnite vs Jade vs Peridot: Three Pale Greens Told Apart

A pale green bead in a listing photograph can be any of the three. Prehnite runs from pale lemon to apple green with a soft, cloudy glow. Nephrite jade covers grey-green to deep spinach green, and jadeite adds white, lavender and a vivid chromium green. Peridot runs olive to yellow-green and is the only one of the three that is routinely transparent. The names get swapped as well: “new jade” has been used as a trade name for prehnite, and older dealer lists called both prehnite and peridot “evening emerald”.

What prehnite is, where it forms and why its colour varies are covered in the prehnite guide. The wider naming matrix for green stones, and how prehnite compares with green phantom and green rutilated quartz, belong to the green crystals guide. BE. sells neither jade nor peridot.

Why do prehnite, jade and peridot get confused?

All three are sold as pale to mid green beads, and the trade has hung jade’s name on prehnite in more than one market. The green comes from iron in each case, but by three different routes. In prehnite, iron substituting for some of the aluminium in the structure can tint an otherwise colourless mineral. In peridot, ferrous iron is part of the olivine formula itself, so the colour is built into the mineral and only its depth changes. In jade, green arrives with iron or, in the finest jadeite, with chromium.

The labels add a second layer. “Grape jade” describes the botryoidal surface of rough prehnite. “New jade” is a trade name with no mineralogical standing. It has been attached to prehnite and to several other green minerals, and none of them is jade. “Cape emerald” and “evening emerald” are older dealer names that borrowed from beryl and were applied loosely across prehnite and peridot. These names describe a look only; the listing still has to name the mineral.

What does each one look like under a loupe?

Texture gives better clues than colour does: prehnite glows from inside like frosted glass, jade shows a compact grain or felt, and peridot is a clear crystal whose far edge appears doubled. A 10× loupe and a window are enough for the first pass. Hold the bead so that daylight enters from behind, then bring it into side light and look at the drill hole.

Prehnite: a cloudy glow with dark needles

Prehnite forms as rounded crusts built from tight bundles of tiny tabular crystals radiating out from a base. A bead cut from that mass is translucent. Light enters, scatters between the sub-crystal boundaries and comes back out as a soft glow, so the bead looks lit from within while the far side stays blurred. The lustre is vitreous to pearly. Many beads carry dark needle-like inclusions, sometimes as single hairs, sometimes as fans; in Mali material, epidote is documented growing with prehnite. Prehnite has one distinct cleavage direction, and a chip at the drill hole tends to show a flat, faintly pearly step.

Jade: a compact grain or a felt of fibres

Both jades are rocks made of interlocking grains, and that is what the loupe finds. Jadeite grains are granular and can look like fine sugar, often with a patchwork of slightly different greens across one bead. A polished jadeite surface can show a faint dimpling, which Gem-A calls the “orange peel” effect: the grains vary in hardness with their orientation, so they polish to slightly different depths. Diamond polishing makes it fainter. Nephrite is built from felted amphibole fibres, so its fracture is splintery and its polished surface has a greasy to waxy look. Light passes through jade evenly at the edges without the glow points of prehnite. There are no needles and no doubling.

Peridot: a clear crystal that doubles its own edges

Peridot is a single crystal of olivine and, in gem grades, transparent. Its birefringence is high at about 0.036, which is enough for a loupe to show the back of a facet or the far rim of a drill hole as a doubled line. Inside, disc-shaped stress fractures called lily pads spread out around tiny included crystals, and small black chromite grains are common. A chip on peridot is glassy and curved, a conchoidal fracture, and looks nothing like the flat step on prehnite.

How do the three compare, property by property?

Specific gravity, cleavage and doubling separate them; hardness and refractive index overlap.

The refractive indices overlap enough that only a refractometer settles the question, and all three fall between Mohs 6 and 7. Specific gravity differs on paper, jadeite at about 3.3 against prehnite at 2.80 to 2.95, but a finished strand's weight also depends on bead count, size and fittings, so heft alone proves nothing. Nephrite, at about 2.95, overlaps with prehnite.

Which one survives a bracelet best?

Jade, by a wide margin, and for a reason that has little to do with hardness. Mohs measures resistance to scratching. Toughness measures resistance to breaking. Jade is middling on the first and near the top on the second, because the interlocking grains stop a crack before it can travel. Nephrite, the softer jade, is the tougher of the two. That is why jade can be carved thin and why a jade bead survives knocks that chip other stones.

Prehnite has the same Mohs value as nephrite and behaves quite differently. The one-direction cleavage and the boundaries between its sub-crystals give a crack a path to follow. Wear shows first at the drill-hole rims and at any edge that meets a desk. Peridot is a little harder, at 6.5 to 7, and its cleavage is poor, but the conchoidal fracture chips at facet junctions, and the International Gem Society notes a sensitivity to acids, including those in perspiration. None of the three is harder than quartz, the grit in everyday dust, so all three pick up fine scratches over years of wear. The Crystal Hardness Chart places them against the rest of the bracelet materials.

In practice, store a prehnite or peridot strand in its own pouch, away from quartz and harder stones. Wipe after wear. Keep both away from ultrasonic and steam cleaners; warm water, a mild detergent and a soft brush are enough.

Which treatments should a seller disclose for each?

For prehnite it depends on the material, for jadeite bleaching and polymer, and for peridot usually nothing. GIA has recorded oiled prehnite from Mali, so treatment cannot be assumed across the mineral, and a written treatment statement matters. Dye concentrates where the stone is porous or cracked, so look at the drill hole and at any surface-reaching fracture under the loupe. If every bead in a strand is the same saturated green and none shows a needle, ask whether it was dyed.

Jade carries a lettered system. Type A jadeite has had nothing done to it beyond a surface wax. Type B has been soaked in acid to bleach out brown or grey iron staining in its fractures, then impregnated with a polymer to fill the voids that the acid opened. Type C has been dyed, and B+C has been bleached, impregnated and dyed. The GIA’s 1992 study on bleached jadeite found infrared spectroscopy to be the only method that gives conclusive evidence of the polymer in every case; other bench tests help but do not settle it on their own. A Type A claim is therefore a laboratory claim. Nephrite is treated less often, and the same letters apply when it is.

Peridot is rarely treated at all. Some cut stones set in closed-back jewellery have been foil-backed to lift the colour, and beads are generally as cut. The full picture by stone is in the Crystal Treatment Chart. For BE. strands, treatment and included minerals are written into each Stone Origin Record under the Crystal 4T™ grading system, and prehnite in the catalogue is untreated.

How should a buyer screen a green bead without damaging it?

Look through it, weigh it in the hand, read the drill hole and ask three questions; leave the steel point in the drawer. A scratch test on a bead that sits between Mohs 6 and 7 gives an ambiguous mark from steel and a clear risk of chipping a cleavage edge. Nothing below needs a tool sharper than a loupe.

What does a bead of each look like in a strand?

• Prehnite: translucent lemon to apple green rounds that glow when backlit; tone varies bead to bead because the rough is a crust, and dark needle-like inclusions show in some or all beads.
• Jade: even, compact rounds from white through grey-green to deep green; nephrite looks waxy and softly lit at the edges, jadeite looks glassier and may show a patchwork of greens within one bead.
• Peridot: small transparent olive rounds or faceted rondelles, often with visible dark specks; clean beads above a few millimetres are uncommon because clean rough of that size is usually faceted instead.

Four checks and three questions

• Transmitted light. Prehnite tends to glow and blur; jade tends to pass light evenly at the rim and stays opaque in the centre; peridot passes light sharply and shows its inclusions in silhouette.
• The loupe. Needles point to prehnite. A sugar-like or felted grain points to jade. A doubled far edge points to peridot.
• Heft. Jadeite and peridot are denser than prehnite, but a strand's weight also depends on bead count, size and fittings, so treat heft as a weak clue. Nephrite and prehnite overlap.
• The drill hole. A flat pearly step means a cleavage chip, typical of prehnite; a splintery, fibrous rim points to nephrite; a curved glassy chip points to peridot.
• Then ask: the mineral name in writing, any treatment, and for jade the type letter.

A laboratory report earns its fee when the asking price is a jade price or the claim is Type A jadeite. For prehnite and peridot sold as beads, a written mineral name and a treatment statement usually settle it. If the strand is already on the wrist and unlabelled, the What Stone Is My Bracelet? hub walks through the same triage for any colour.

The prehnite strand belongs to The Flow series. For the quartz side of the green catalogue, the Green Phantom Quartz guide explains how chlorite phantoms form.

1. Wikipedia: Prehnite. Formula, Mohs 6 to 6.5, specific gravity 2.8 to 2.95, refractive index, cleavage and habit.
2. International Gem Society: Prehnite Value, Price and Jewelry Information. Gem-material specific gravity, birefringence, lustre and fracture.
3. GIA: Jade. Jadeite and nephrite as two minerals; hardness values; both extremely tough for their hardness.
4. Wikipedia: Jade. Type A, B, C and B+C definitions; nephrite tougher than jadeite.
5. Wikipedia: Jadeite. Formula, Mohs 6.5 to 7, specific gravity and refractive index; interlocking crystals and toughness; bleaching and polymer impregnation.
6. Wikipedia: Nephrite. Tremolite-actinolite composition, Mohs 6 to 6.5, specific gravity about 2.95, refractive index, splintery fracture.
7. Gem-A: Understanding Jade and Its Importance in China. The “orange peel” effect on polished jadeite and its cause.
8. Geology.com: Jade. Hardness versus toughness; Type A, B and C treatments; jade misnomers.
9. GIA Gems & Gemology, Fall 1992: Identification of Bleached and Polymer-Impregnated Jadeite. Infrared spectroscopy as the conclusive detection method.
10. GIA: Peridot. Olivine identity, intrinsic yellow-green colour, double refraction 0.035 to 0.038, hardness.
11. Wikipedia: Peridot. Formula, Mohs 6.5 to 7, refractive index 1.64 to 1.70, birefringence 0.036, cleavage, lily-pad and chromite inclusions.
12. International Gem Society: Peridot Value, Price and Jewelry Information. Specific gravity, doubling, lily pads, acid sensitivity, foil backing, cleaning advice.
13. Schumann, W. Gemstones of the World, revised edition. Sterling. Reference values for prehnite, jadeite, nephrite and peridot.