Glowing Glass: Uranium, Manganese, Cadmium and Lead Crystal Under UV Light

October 29, 2026

Uranium, manganese and cadmium glowing glass guide header, Oddly Darling Vintage

Shine a black light on a shelf of vintage glass and some pieces light up like magic. The glow comes from minerals added to the glass, and each one glows its own color. Here's how to make them glow and how to tell them apart.

How to Make Glass Glow

Use a longwave UV flashlight labeled 365 nm. These give the clearest results and are inexpensive. 395 nm lights are common and cheaper, but they give off visible purple light, and most glass other than uranium won't react to them.
Make it dark. A dark room, closet, or nighttime makes even faint glows easy to see.
Hold the light close and look at the glass itself, not the reflection.
Shortwave UV lights make some glass glow differently, but they can harm eyes and skin. Most collectors stick to longwave; if you use shortwave, wear UV-blocking glasses.
Never shine any UV light into anyone's eyes.

Uranium Glass: Bright Neon Green

Uranium glass glows a vivid, neon green, the brightest and most famous glow. It was made from the 1800s until the 1940s, when uranium was restricted, and again in smaller amounts from the late 1950s, with makers like Mosser using it in the 1970s.

Vaseline glass is transparent yellow to yellow-green uranium glass, named for its resemblance to old petroleum jelly.
Custard glass is opaque, creamy yellow uranium glass.
Green or yellow Depression glass and Burmese glass (pink shading to yellow) can contain uranium too.
Uranium glass can glow even when it looks clear, pink, or blue in daylight, so test everything.
Only uranium glass is radioactive, so a Geiger counter can confirm it.
Is it safe? The radiation is very low and generally considered safe to handle and display. Many collectors choose not to eat or drink from it, especially acidic foods, and it should never be ground or sanded.

Manganese Glass: Softer Green

Manganese was added to clear glass, mostly from the late 1800s to about 1915, to cancel out the green tint from iron in the sand. Under a 365 nm light it glows a softer, duller green or yellow-green that's often mistaken for uranium.

Unlike uranium glass, most manganese glass won't glow under a 395 nm light, and it isn't radioactive.
Over years in the sun, manganese glass slowly turns lavender or light purple, called "sun-purpled" glass. Old bottles, insulators and pressed glass are common examples.
Clear, slightly purple pressed glass that glows faint green is likely manganese glass from before World War I.
Some glass was purposely irradiated to turn it purple, so very deep purple isn't always natural aging.

Cadmium Glass: Orange to Red

Cadmium and selenium give glass bright yellow, orange and red colors, popular in mid-century art glass and "amberina" style pieces. Under UV, cadmium glass usually glows orange to orange-red.

Many Italian and other mid-century orange and red art glass pieces glow this way.
Cadmium is a toxic metal, so use cadmium glass for display rather than food or drinks.

Lead Crystal: Soft Blue

High-lead crystal often glows a soft, ethereal blue or blue-white under UV light. This is the blue glow that confuses so many people.

Lead crystal was prized for its sparkle, weight and ring. Fine cut crystal decanters, stemware and bowls often glow blue.
A blue glow, plus a heavy feel and a clear, bell-like ring when gently tapped, points toward lead crystal.
Collectors are still learning exactly what causes the blue glow, so treat it as a strong clue rather than proof.
Lead can leach into drinks over long periods, so avoid storing wine or spirits in vintage lead crystal decanters. Serving a drink now and then is generally considered fine.

Learn more in our guides to cut glass vs pressed glass and pressed glass vs cut crystal.

Other Glows You Might See

Modern glass may glow very faintly, or not at all.
Glues, repairs and plastics often glow differently from the glass around them. A black light is a great way to spot old repairs on glass and china.