I have a set of cathedral hands that are a beautiful "rainbow" blue if looked at in the right angle.
Lately I've came across some watches with hands that look ANODIZED blue ... are they installing these to try to get the "rainbow aged" blued look, or are they really just naturally aged to a blue color?
Thanks! 
In reply to It's my belief that that the… by mybulova_admin
In reply to They are blued using a heat… by JimDon5822
The Deadly Blue Watch Hands
We may all be forgetting The Radium Girls, the timepiece workers at US Radium in Orange NJ that were all poisoned to death painting watch dials, hands and markers with liquid Radium.
In the late 1920s through mid 1930s, radium was used to make aircraft cockpit gauges glow in the dark. This process transfered over to the watch and clock industry. Little vials of Radium were sent to jewelers and clocks had vials hidden in the back cases so a customer could repaint the hands.
Less to say, cobalt 40 had a lifespan of 2000 years. The entire section of land formerly occupied by US Radium in Orange, NJ is quarantined to this day and probably forever.
These hands found on name brand pocket watches and early wrist's still have traces in many cases of active radium. And yes, they are Blueish is color. When I come across these hands in my shop, I ultrasonically clean immediately. And try not to handle them with my bare fingers.
The Radium Girls is a tragic story lost in time. It impacted the watch industry and the 1930s Workers Reform Act was initiated by Congress which still today protects the rights of workers in a hazardous manufacturing environment.
John V.
Time & Again
In reply to The Deadly Blue Watch… by JEV1A
"With the discovery of Radium (in my opinion rediscovery), the society went bananas and started sticking radium into just about everything. We are talking about soap, toothpaste, male ED enhancements, chocolate, tea, coffee, food, cigarettes, cosmetics, bath salts etc."
Source: 19th century: Radium Heating Systems? | KD's Stolen History Blog
In reply to "With the discovery of… by 1955mercury
In reply to "With the discovery of… by 1955mercury