Tritium, Luminova and Chromalight: How Lume Dates a Watch

Tritium and Luminova are the two luminous materials that separate a vintage watch from a modern one. Tritium is a mildly radioactive hydrogen isotope that Rolex, Patek Philippe and most Swiss brands painted onto dials and hands from the early 1960s until about 1998; it glows on its own for a decade or two, then fades and turns cream, which is the patina collectors pay for. Luminova, followed by Super-LumiNova, is a non-radioactive pigment that charges from light, stays white and does not age, and it took over at the end of the 1990s. Chromalight is Rolex's own version of that chemistry, introduced in 2008 and glowing blue rather than green. Because each material carries its own dial markings and its own way of ageing, lume is one of the fastest ways to date a watch and to spot a replaced dial or hands. Bizak & Co. sources tritium-era and modern references to order; the used Submariner collection shows the kind of watches this guide describes.

Last reviewed on September 21, 2026 by Filip Biczak. Prices are dated observations, not quotes.

What is the difference between tritium and Luminova?

Tritium lume is a phosphor, usually zinc sulphide, mixed with a tritium compound. The tritium decays and its radiation makes the phosphor glow continuously, with no need for light. Its half-life is about 12.3 years, so a dial from 1985 has gone through more than three half-lives and gives off almost nothing today; what you see in the dark on a vintage watch is mostly the phosphor reacting to the light you just shone on it, if it reacts at all. The phosphor also degrades and discolours as it ages, which is why tritium plots drift from white to ivory, cream, custard and, on some dials, orange or brown.

Luminova is a strontium aluminate pigment developed by the Japanese company Nemoto in the early 1990s. It is not radioactive. It absorbs light, then releases it over several hours, bright at first and dimming through the night. It does not decay chemically, so a 1999 Luminova dial looks the same colour today as it did new. Super-LumiNova is the Swiss-made version of the same chemistry, produced under licence from about 1998, and it is what almost every Swiss watch has used since.

How each lume behaves: a comparison

The table describes Rolex practice; other brands changed over at slightly different dates, and Patek Philippe and Audemars Piguet moved from tritium to Super-LumiNova across the same late-1990s window. The Federation of the Swiss Watch Industry is the industry body behind the "Swiss Made" marking that appears on every post-tritium dial.

How do dial markings date a tritium watch?

Swiss regulations required a dial to state that it contained tritium and, from the 1960s, to state that the activity was below a limit. Rolex printed "SWISS - T < 25" at the foot of the dial on most sports models, meaning tritium below 25 millicuries, and "T SWISS T" on many dress and Datejust dials. A dial marked this way was made before about 1998. In 1998 and 1999 Rolex went through a short transition in which dials were printed "SWISS" only, sometimes with Luminova and occasionally with tritium; those transitional dials are now collected in their own right. From about 1999 the marking became "SWISS MADE" and the lume was Luminova, then Super-LumiNova. On a Submariner 16610, for example, the sequence runs tritium to about 1998, "SWISS only" for a year or so, then Super-LumiNova through the end of production in 2010. The Submariner 1680 and the GMT-Master 1675 are tritium throughout; the GMT-Master II 16710 spans all three.

Why does tritium lume turn cream, and why do collectors want it?

Two things age. The tritium decays, which does no visible harm, and the zinc sulphide phosphor yellows as it is bombarded and as it reacts with moisture and light over decades. The result is a warm colour that ranges from ivory to deep orange, and because the same batch of lume was applied to dial and hands at the factory, an untouched watch shows the same tone on both. Collectors want it because it cannot be reproduced honestly: a factory-fresh Luminova dial will never look like a 1970s tritium dial, and a service-replaced dial on a vintage watch breaks the match between dial, hands and bezel pearl. The Phillips watch department and Sotheby's watches catalogues describe lume condition in almost every vintage lot for that reason; even, unrestored patina is what separates the top of an estimate from the bottom.

Is tritium lume dangerous?

Inside a cased watch, no. Tritium emits low-energy beta particles that the crystal and case stop entirely, and the activity on a dial was limited by regulation to a fraction of what a modern exit sign contains. The precautions are for the watchmaker, not the wearer: do not scrape old lume, do not breathe the dust, wash hands after handling loose dials and hands. Radium, which tritium replaced in the early 1960s, is a different matter; it emits gamma radiation, it stays active for over a thousand years, and radium dials should be stored away from people and handled by someone who knows what they are doing. If you are not sure whether a pre-1965 dial is radium, treat it as though it is.

Luminova, Super-LumiNova and Chromalight: what changed after 1998?

• Luminova, 1998 to about 2000. The first non-radioactive lume on Rolex dials, applied during the "SWISS only" transition and the first "SWISS MADE" dials. Stays white; green glow.
• Super-LumiNova, about 2000 onward. The Swiss-licensed version, brighter and more consistent. Rolex used it on the Submariner 16610, GMT-Master II 16710 and the early ceramic-bezel watches such as the GMT-Master II 116710LN of 2007. Audemars Piguet and Patek Philippe still use it, and the current Patek Philippe Nautilus and Audemars Piguet collections are lumed with it.
• Chromalight, 2008 onward. Rolex's proprietary formulation, first seen on the Deepsea 116660 and then rolled out to the Submariner 116610 in 2010, the GMT-Master II, Explorer and the rest of the professional range. It glows blue, which Rolex says is easier to read in low light, and Rolex has claimed a longer glow than standard Super-LumiNova, with a figure of up to eight hours quoted for recent versions. In daylight it is white and indistinguishable from Super-LumiNova; you need darkness to tell them apart.

For a buyer, the practical rule is: green glow means Luminova or Super-LumiNova and a watch from about 1998 to the late 2000s; blue glow means Chromalight and a Rolex from 2008 or later; no glow at all, with cream plots, means tritium and a watch from before 1998.

How to use lume to check a vintage dial and hands

• Match dial to hands. Plots and hands should be the same colour under daylight and behave the same under a UV torch. White hands on a cream dial mean the hands were replaced at service; Rolex fitted Luminova hands to tritium watches as a matter of course from the late 1990s.
• Match marking to serial. A "SWISS MADE" dial in a watch whose serial dates to 1990 is a service dial. A "SWISS - T < 25" dial in a 2003 serial has been swapped in, usually to make the watch look older or more collectable.
• Check the bezel pearl. On Submariners, GMT-Masters and Sea-Dwellers the luminous pearl at 12 on the bezel insert should age with the dial; a bright white pearl on a cream dial is a replaced insert or a replaced pearl.
• Look for relume. Re-applied lume sits proud of the dial, has uneven edges, and often glows strongly under UV where original tritium would not. Some relumes are aged with pigment to mimic patina; the texture gives them away under magnification.
• Tropical and burnt dials. A dial whose black surface has turned brown is "tropical" and desirable; a radium dial with dark halos around the plots is "burnt", which is a cosmetic fault on most references and a virtue on a few.
• Ask for the last service record. Rolex service centres replaced tritium dials and hands routinely until the 2000s if the customer did not say otherwise; a full-service watch from that era is more likely than not to carry service lume.

Our authentication process puts every vintage dial under UV and magnification before we describe it, and our vintage Submariner authentication guide goes deeper on dials and inserts.

What does lume do to the price?

On a modern watch, nothing; Chromalight and Super-LumiNova are consumables that Rolex renews at service and nobody pays a premium for either. On a vintage watch, lume is a large part of the price. The gap between a Submariner 1680 with an even, original tritium dial and the same reference with a service dial is routinely a third or more of the watch's value, and on rarer references it can be the difference between a reference-book example and a runner. The same is true, on a smaller scale, for the last tritium 16610s and 16710s from 1997 and 1998, which trade above the Luminova watches that followed them. On September 21, 2026 Bizak's sourced catalogue listed a Submariner 1680 at US$11,159, a Submariner 16800 at US$6,974, and Submariner 16610 examples from US$8,369 to US$13,019, all pre-owned and sourced to order; the spread within the 16610 range is largely year, set and dial condition, with tritium dials at the top. Those are dated observations that will move. The Submariner price guide explains how to compare quotes for the same reference in different condition.

Quick answers

What is the difference between tritium and Luminova?

Tritium is a weakly radioactive isotope that made dial lume glow on its own and was used until about 1998; it fades and turns cream with age. Luminova and Super-LumiNova are non-radioactive pigments that charge from light, stay white and have been used since the late 1990s.

How can I tell if a watch has tritium lume?

Look at the foot of the dial: "SWISS - T < 25", "T SWISS T" or "T SWISS MADE T" means tritium. Tritium plots on a watch older than 25 years are cream to orange in daylight and barely glow, if at all, in the dark.

Is tritium in a watch dangerous?

Not to the wearer; the case and crystal stop the low-energy radiation completely. The care is for watchmakers handling loose dials and hands. Radium, used before the early 1960s, is far more active and should be handled as hazardous.

What is Chromalight?

Rolex's proprietary luminous material, introduced on the Deepsea in 2008 and used across the professional range since. It glows blue rather than green, looks white in daylight and does not age like tritium.

Does tritium lume still glow?

Barely. Tritium's half-life is about 12.3 years, so a 1980s dial has lost most of its activity, and the phosphor has degraded too. A vintage dial that glows brightly under a torch has usually been relumed.

Request a sourcing quote for a tritium-era or modern reference

Tell us the reference, whether you want an original tritium dial or a serviced watch, the condition you will accept and your budget and timing, through our sourcing enquiry form. We confirm the specific watch, photographs under daylight and UV, papers and final price before you commit. Catalogue entries: Submariner 1680, Submariner 16800, Submariner 16610; browse the used Submariner collection, the pre-owned watches collection, or sell or trade your vintage Rolex.

Related reading: Vintage Submariner authentication guide · Submariner 16613 Bluesy guide · Submariner 16610LV Kermit guide · Submariner price guide.