UV light ranges & use for Gemstones

[user 4485]

Black light is UV.
There are different waves (long/short) so not sure what works best on gemstones.

 

[LONEWOLF]

Yes black light is UV.
There are different waves (long/short) so not sure what works best on gemstones.

No Matt different spectrum to a true UV...

LW....

 

[user 4485]

No Matt different spectrum to a true UV...

LW....

I always thought the lights were either shortwave or longwave just like the torches for gems.
Have seen both longwave lights & torches at ~365nM.

 

[LONEWOLF]

Yes but its on the very high end of the spectrum... Most UV sensitive rocks wont glow under this spectrum...

UV covers the wavelength range 100-400 nm and is divided into three bands: UVA (315-400 nm) UVB (280-315 nm) UVC (100-280 nm).

Ultraviolet light encompasses a wide range of wavelengths, but most blacklight applications utilize a narrow range of ultraviolet radiation (UV-A) to produce fluorescence effects - specifically between 350 and 400 nm (nanometers).

LW..

 

[grubstake]

Yes but 'black light' is not in the UV spectrum.. Close tho .. Thats why some stones will show up under both and some only under UV... Catches out the unwary when it comes to buy... Very misleading..

LW..

Nope, Matt's correct - there's three ranges of UV light: A, B and C. "Black light" is UVA.

 

[LONEWOLF]

Thats correct BUT UVA is not a good viewer for Rocks as most react to the lower spectrums only... Anything over 365 or more is not a good light... 280-315 Is great for rocks...

 

[user 4485]

Nope, Matt's correct - there's three ranges of UV light: A, B and C. "Black light" is UVA.

View attachment 10728

That's how I took the ranges to be but shortwave UV up to 280nM & longwave UV 315 to 400nM which includes black light.

 

[LONEWOLF]

Yes but for rock viewing under 365 is best so that rules out the black light in most cases...... Some rocks like Mangano-calcite will glow under any source of UV if Heat treated. above 400deg C for 4hrs and left to naturally cool... Then they really pop with colour...

On another note, You can have 5 stones like Rubies from the same location and only 1 or 2 might glow... Or even none... Up to nature to decide that one..
.
LW...

 

[LONEWOLF]

This explains it better than me...
https://www.mineralab.com/AboutUVLi...UV is produced by,from 320 to 400 nanometers.
LW...

 

[user 4485]

International Gem Society: For gem identification, we use longwave (LW) light, 315 to 400 nm, and SW light, 200 to 280 nm. The range in between isn’t used.

Even though most gemstones fluoresce better in the UV shortwave range others, like ruby, are better in the UV longwave range, which is why serious punters have both ranges no doubt.
Interesting that from 280 to 315 isn't used.
There are a lot that seem to be promoted at 365nM. Possibly due to still able to get a reaction & in the safer range?
The UV shortwave range is pretty hazardous & requires protective glasses etc. if anyone is thinking about using them.

 

[user 4485]

On another note, You can have 5 stones like Rubies from the same location and only 1 or 2 might glow... Or even none... Up to nature to decide that one..
.
LW...

Would be true for other stones like sapphire (low iron) & zircon but as far as I can find all rubies will fluoresce under the correct UV light.

 

[Hawkear]

Mineral fluorescence was something that got me really interested in geology, when I saw displays of fluorescing minerals in the Vic Mines Department mineral museum as a kid.
Here's a link to a you tube on the science of fluorescence, for those who want to delve deeper.

 

[LONEWOLF]

It all depends on what stone got more of the Reactive element than the other...

2 very good sites that I use are listed bellow..

I blame this Fella for My Fetish on Glow Minerals... Thanks Graham..
https://fluoromins.com.au/about-us/
And some more info can be found here...
https://uvminerals.org/
LW...