Yellow Crystal Bracelets: Citrine, Rutilated or Obsidian?

A yellow crystal bracelet can mean three different materials in the same shop window. One is a transparent bead with warm colour all the way through. One is clear quartz with fine metallic threads running inside each bead. One is a black bead that turns gold for a moment when the wrist moves, then goes dark again. All three sell under gold and yellow labels, and they behave differently once they are on a wrist.

Citrine and golden rutilated quartz are both quartz, and Citrine vs Golden Rutilated Quartz compares the two in depth. Gold sheen obsidian is the odd one out on a wrist: a glass among minerals, softer, and gold only when the angle is right. Sapphire, topaz, pyrite, amber and the other stones sold as yellow or gold are mapped in yellow and gold crystals.

Where does the gold come from in each stone?

The gold comes from three different places: the quartz itself, a second mineral trapped inside the quartz, or a structure inside glass that reflects light at one angle. Citrine is the transparent pale yellow to brownish orange variety of quartz, SiO₂, and the colour belongs to the crystal. Iron is the usual explanation for the yellow, though the colour centre is still debated. Cut the bead anywhere and the colour continues through it. The Citrine Guide covers formation and origins.

Golden rutilated quartz is a different arrangement. The host is quartz again, usually colourless, pale or smoky, and the gold belongs to rutile, titanium dioxide, TiO₂, which grew as needles that the quartz enclosed. Rutile has an adamantine to metallic lustre and a refractive index far above that of quartz, so each needle returns light like a length of fine wire. Take the needles away and the bead would be plain clear quartz. Why the needles come in gold, red, silver or black is explained in Rutilated Quartz Meaning.

Gold sheen obsidian is volcanic glass. Silica makes up 70 per cent or more of it by weight, yet there is no crystal lattice, because the lava cooled too fast for one to form. The gold is a flash that appears when light meets a layer inside the glass at the right angle. A 2001 study of Mexican sheen obsidian found flow-aligned lenticular regions of a second rhyolite glass, or stretched vesicles, whose refractive index differs from the surrounding glass by up to 0.04, and placed the sheen at the interface between the two. A 2007 study of fire obsidian from Oregon found something else: layers of nanometre-scale magnetite crystals 300 to 700 nm thick, producing colour by thin-film interference. The mechanism depends on the deposit. Gold Sheen Obsidian Bracelet goes through the evidence source by source, and Sheen, Adularescence & Tyndall sorts sheen from the other named effects.

How do the three compare bead for bead?

Matching decides whether a strand reads as one piece. Citrine strands are the simplest of the three to match, because citrine’s colour runs through each bead with no needles or sheen to line up. Rutilated strands are the hardest: needle density varies within a single crystal, so two beads cut from the same rough can hold a few needles or dozens. Obsidian strands are matched on two other things: how much of each bead carries sheen, and whether the flash travels the same way on every bead when the strand turns.

What does each bead do under office light and in sunlight?

Citrine keeps its colour under almost any light, golden rutilated quartz needs directional light, and gold sheen obsidian needs a moving angle. Office lighting is diffuse and comes from above. Under it, a citrine bead shows the same warm yellow it shows anywhere, because body colour comes from light absorbed inside the bead, and absorption looks the same from every angle. A rutilated bead loses contrast: the needles are still there, but with no point source to catch they read as quiet grey-gold lines inside pale quartz. A gold sheen obsidian bead under a ceiling panel usually reads as a black bead.

Move the same three beads to a window or outside. Citrine gets brighter, and the orange component shows at the thin edge. The rutile needles start to flash one at a time, since each needle is a small mirror with its own orientation and the sun is a small enough source to light them separately. Obsidian changes the most. The internal layer catches the sun at one angle, so the flash appears, slides across the bead as the wrist rotates, then goes. Somebody who spends the day under office panels and wants the gold visible at the desk should look at citrine first. Somebody who wants the bracelet to do something when they step outside should look at the other two.

Which one holds up to daily wear?

Both quartz stones resist wear better than obsidian on a wrist. Quartz sits at Mohs 7, above ordinary steel, so a citrine or rutilated bead resists scratching from keys, buckles and desk edges. Obsidian sits around 5 to 6 and fractures conchoidally, the way bottle glass does. A steel edge can mark it, and a knock against a table can take a chip out of the rim of a drill hole. Reference guides warn that it lacks toughness and chips on impact, and flag rings and bracelets as the pieces that take the most knocks. An obsidian bracelet still works for a wearer who takes it off before the gym, the garden and the washing-up.

Rutilated quartz has a wear detail of its own. Rutile is softer than quartz, 6 to 6.5 against 7, and where a needle reaches the surface of a bead the polish can pit at that spot. Dense-needle beads show this more than sparse ones. It is cosmetic, and much of it is already there when the bead leaves the polisher, so check under a lamp before buying. Citrine has no second mineral to worry about; its risk is the drill-hole chipping any quartz bead carries, and that is rare with a cleanly drilled bead.

Stringing affects wear too. BE. strands are mostly strung on steel wire with a magnetic clasp, with a few pieces on elastic. On wire, beads sit still against each other. On elastic, they stretch apart and snap back with every pull, which is where bead-to-bead abrasion tends to start, and softer beads show it first.

What should you ask about treatment and matching before paying?

Ask a different question of each stone: colour history for citrine, host and needle identity for golden rutilated quartz, glass identity and source for obsidian. Natural-colour citrine is rare, and some citrine on the market is heated amethyst. Heated citrine is still quartz and the colour is stable; suitable amethyst can lose its violet when heated and turn yellow to orange, at temperatures that vary from stone to stone. The purchase question is whether the seller writes that colour history down. The Crystal Treatment Chart lists which stones are routinely treated and what a listing should state.

The golden rutilated quartz in BE. strands is untreated. For any strand, the questions are whether the host is natural quartz, whether the golden needles are rutile, and whether the needle density on the listing matches the beads in the photograph. Glass imitations of rutilated quartz exist, and the first of those questions catches them. Golden Rutilated Quartz: Price & Quality lists the five variables that move price and how to read a strand for each of them.

For gold sheen obsidian the first question is identity. Goldstone, a manufactured glass full of copper flakes, and resin loaded with metallic glitter both sell as gold-look beads. Goldstone sparkles at every angle from many separate flakes. Gold sheen obsidian shows a band of gold that moves with the angle. The second question is source, since the sheen mechanism differs between deposits. The third question is treatment, and BE.'s gold sheen obsidian is untreated. The last is matching: look for a photograph of the whole strand tilted toward the light, so the flash on every bead shows at once.

None of the three can be identified from a product photograph alone. BE. records lot and treatment status for every strand and grades each one under Crystal 4T™, which sets out what each reading covers and how a strand earns its grade.

Which gold suits which wearer?

Choose by what the eye should meet first: colour, structure or a flash.

Wants warm transparent colour

Citrine. The colour is in the bead, it reads under any lamp, and a well-matched strand looks like one continuous tone all the way round the wrist. Ask for the colour history in writing, look at the rim of each drill hole, and choose the saturation that suits the skin it will sit on. Pale citrine sits quietly on a fair wrist. The orange end holds up on darker skin.

Wants visible structure inside the bead

Golden rutilated quartz. Every bead is a small window onto needles that grew before the quartz closed around them, and no two beads repeat. Decide first between a clear host, where each needle stands alone, and a dense strand, where the needles fill the bead and read as a gold mass. Then check that the needle density is consistent along the strand and that no bead has a polish pit at a needle tip.

Wants dark with a flash

Gold sheen obsidian. On the wrist it reads as a black bracelet with a gold that comes and goes. Check that every bead carries sheen, that the flash moves the same way across the strand, and that the drill holes are clean. Take it off before rough work.

The two quartz strands sit in The Prism series alongside the other colour and inclusion quartzes. Gold sheen obsidian sits in The Anchor series with the dark stones.

1. GIA, Citrine: transparent pale yellow to brownish orange quartz; Mohs 7; natural citrine is rare, and heated amethyst is sold as citrine.
2. GIA, Citrine Description: colour range and the heat treatment of pale amethyst to yellow.
3. Wikipedia, Citrine: colour cause still debated, with iron-related and aluminium-related colour centres both proposed; amethyst can turn yellow to orange when heated.
4. Wikipedia, Obsidian: 70 per cent or more SiO₂ by weight; amorphous; Mohs 5 to 6; conchoidal fracture; sheen and fire varieties.
5. Wikipedia, Rutile: TiO₂; Mohs 6 to 6.5; adamantine to metallic lustre; refractive index 2.61 to 2.91.
6. Ma, C., Gresh, J., Rossman, G. R., Ulmer, G. C. and Vicenzi, E. P. (2001). Micro-analytical study of the optical properties of rainbow and sheen obsidians. The Canadian Mineralogist, 39, 57 to 71: Mexican sheen obsidian; second rhyolite glass in flow-aligned lenticular regions; refractive index difference up to 0.04.
7. Ma, C., Rossman, G. R. and Miller, J. A. (2007). The origin of color in "fire" obsidian. The Canadian Mineralogist, 45, 551 to 557: Glass Buttes, Oregon; magnetite nanocrystal layers 300 to 700 nm thick; thin-film interference.
8. Gem-A, A Passion for Working Fire Obsidian: flow bands 300 to 700 nm thick enriched in nanometric magnetite; found in small dykes in southeast Oregon.
9. Geology.com, Obsidian: hardness about 5.5; lacks toughness, chips on impact; durability concerns for rings and bracelets.
10. Schumann, W. Gemstones of the World. Sterling: quartz, citrine and obsidian property tables.
11. Webster, R. Gems: Their Sources, Descriptions and Identification. Butterworths: quartz varieties, rutile inclusions and natural glasses.