I have, what I believe, is a 1944 Clipper that has luminous hands and what appears to be luminous numerals on the dial.
I was going to have the numerals re-lumened in white, but after carefully cleaning a portion of the dial, it appears that the numerals may have been originally green.
Were the numerals on a black dial from the mid-forties green or white?
Different additives in the radium paint were used to give different colour to the lume, along with zinc sulphide to make the numbers/hands 'glow'.
A copper 'dope' was added to turn the colour green, silver to make a blue-green colour, and most rarely seen was copper/magnesium for a yellowy orange light.
An advert for Illinois wrist watches mention that "in daylight the numbers and hands are a beautiful blue" on their military style radium dial watch, but no mention is made of the colour seen at night.
The most common colour for Radium paint was a pale green. If you are thinking of re-luming this watch, I recommend reading any of our discussions on Radium and the hazards involved in doing this. Here are the quick facts:
Radium has a half life of 1601 years, and the watch will remain radioactive even after the paint is removed.
The alpha particles exit the watch through the front, and are blocked to the rear by the movement and case.
Ingestion is the biggest hazard, but removing the radium contaminates the work area and all tools used to do this.
Radium is seen by the body as Calcium, and is imported into the bones, causing the classic 'Radium Ache' that never goes away.
The average watch dial contains approximately 1 microgram of radium, and for comparison, that is ten times the 'tolerance dose' for ingestion set at the time of the Manhattan project.
I have personally measured single hands that have emitted 60 micro Sieverts per hour, and for comparison, astronaut exposure is limited to 6 Sieverts per year. Doses in excess of 1 Sievert in a short period of time leads to radiation poisoning and usually death. A dose of 1 Sievert means a 5.5% chance of eventually developing cancer. A micro Sievert is .000 001 Sievert.
Radium watches are safe to wear, it is only when the Radium is flaking or removed, made aerosol, or in any way ingested by breathing, or through mucous membranes, that the real hazard exists.
You cannot simply replace the depleted Sulfide to make it glow again.
Radium was used in watches until the early 60's and in clocks until 1978, despite the awareness that it was extremely toxic.
We no longer re-lume radium dials at all.