Wavelength of UV light for viewing fluorescence in diamonds

[jstarfireb]

What's the best wavelength of UV light to use for viewing fluorescence in diamonds? I am upgrading my ACA pendant to a diamond with medium blue fluor, and I want to buy an inexpensive penlight or flashlight that has the right wavelength to make my diamond glow electric blue. I saw 375, 390, and 395nm flashlights on amazon.com. The Wikipedia on diamonds mentions 365nm as an example of long-wave UV light. Does that mean I should go for the 375? Thanks in advance!

 

[whatmeworry]

Re: Wavelength of UV light for viewing fluorescence in diamo

365 nm is the gemological standard definition for longwave UV. So the closer you can get, the better but I can easily get fluorescence with a 385 nm LED. I had a friend check out my LED UVs with a spectrometer and the 385 nm LEDs were pretty much as advertised. One that was advertised as 365 nm was really about 378 nm.

 

[yssie]

Re: Wavelength of UV light for viewing fluorescence in diamo

365 nm is the gemological standard definition for longwave UV. So the closer you can get, the better but I can easily get fluorescence with a 385 nm LED. I had a friend check out my LED UVs with a spectrometer and the 385 nm LEDs were pretty much as advertised. One that was advertised as 365 nm was really about 378 nm.

I just learnt something new from this post, thank you wmw!


According to wiki blue fluor (N3) characterised by absorption at 415nm - http://en.wikipedia.org/wiki/Crystallographic_defects_in_diamond

 

[jstarfireb]

Re: Wavelength of UV light for viewing fluorescence in diamo

OK, so do you guys think something like this would be good for viewing fluor? I'm looking for one that's relatively inexpensive and takes "normal" batteries (AA, AAA, etc.).

http://www.amazon.com/Counterfeit-Ultraviolet-LED-BlackLight-Flashlight/dp/B001XJUDHM/ref=sr_1_2?ie=UTF8&s=sporting-goods&qid=1301412494&sr=8-2

 

[John P]

Re: Wavelength of UV light for viewing fluorescence in diamo

What's the best wavelength of UV light to use for viewing fluorescence in diamonds? I am upgrading my ACA pendant to a diamond with medium blue fluor, and I want to buy an inexpensive penlight or flashlight that has the right wavelength to make my diamond glow electric blue. I saw 375, 390, and 395nm flashlights on amazon.com. The Wikipedia on diamonds mentions 365nm as an example of long-wave UV light. Does that mean I should go for the 375? Thanks in advance!

Hello jstarfireb. Congrats on the upgrade - and cool idea.

Good info from WMW and likely exactly what you needed to know. GIA uses both long-wave (@ 365 nm) and short-wave (@ 254 nm) but SW is mainly for lab ID purposes. Of course some specimens like the Hope Diamond do fluoresce and phosphoresce to SW so it's fun to check both aspects with any stone...but you're only looking for LW, I expect.

An appraisal-quality unit will have both (LW 366 nm SW 254 nm). The GIA store sells this for $879.
http://www.eickhorst.com/en/gemmological-instruments/uv-lamps/multispec/features/

I keep one of these Kassoy LWs next to my loupe in my briefcase. It's 380 nm. As WMW implied that will do just fine.
http://www.kassoy.com/9-uv-led-light.html

This may be even more up your daily-use-alley? Inexpensive UV keychain-lights. Listed at 370 nm (but ymmv).
http://www.photonlight.com/categories/LED-Flashlights/By-Brand:-Photon/?sort=bestselling

I've seen those Photon keychain-lights offered by diamond-tool sellers for a higher markup. When I have seen them used they appear to do well at fluorescence-excitement. For practical applications the $25 Kassoy is profoundly stronger, logically.

Photos next, please.

 

[John P]

Re: Wavelength of UV light for viewing fluorescence in diamo

OK, so do you guys think something like this would be good for viewing fluor? I'm looking for one that's relatively inexpensive and takes "normal" batteries (AA, AAA, etc.).

http://www.amazon.com/Counterfeit-Ultraviolet-LED-BlackLight-Flashlight/dp/B001XJUDHM/ref=sr_1_2?ie=UTF8&s=sporting-goods&qid=1301412494&sr=8-2

That one looks good too. And with a AAA battery it's probably stronger than the key-chain versions.

 

[whatmeworry]

Re: Wavelength of UV light for viewing fluorescence in diamo

OK, so do you guys think something like this would be good for viewing fluor? I'm looking for one that's relatively inexpensive and takes "normal" batteries (AA, AAA, etc.).

http://www.amazon.com/Counterfeit-Ultraviolet-LED-BlackLight-Flashlight/dp/B001XJUDHM/ref=sr_1_2?ie=UTF8&s=sporting-goods&qid=1301412494&sr=8-2

That should work great.

 

[jstarfireb]

Re: Wavelength of UV light for viewing fluorescence in diamo

Thanks guys! I think I'll pick up that little one I linked to. I'll do my best to get pics, but my camera is about 8 years old, and I don't see myself getting a new one any time soon!

 

[jstarfireb]

Re: Wavelength of UV light for viewing fluorescence in diamo

OK, guys, the penlight and the diamond are both here, so I tried to snap some pics. My digital camera was completely worthless here, but my Droid actually picked it up reasonably well. However, it got the colors all wrong. The real color isn't purple like this, but it's bright blue.

 

[jstarfireb]

Re: Wavelength of UV light for viewing fluorescence in diamo

Some more...hope you guys like it! Now, would I be completely crazy if I carried the penlight around during my normal daily activities and stared at my diamond every once in a while...?

 

[MakingTheGrade]

Re: Wavelength of UV light for viewing fluorescence in diamo

Super cool!

 

[John P]

Re: Wavelength of UV light for viewing fluorescence in diamo

Nice! Do you have an auto-timer on your camera? Perhaps using the macro-setting plus auto-delay from hitting the button until the camera takes the snapshot would get a more in-focus image... No worries if not. They are cool as-is.

 

[Karl_K]

Re: Wavelength of UV light for viewing fluorescence in diamo

neat pictures.
The common and cheap uv leds are around 385nm +/- 5.
The are often falsely advertised as being lower.
A good indication is cost... a 385nm wholesales for around 10 cents for the led when you buy in bulk, a true 365nm was in the 10-12 dollar range wholesale each just for the led last I checked.
So even in a $25 device odds are it will not have a 365nm led.

 

[Karl_K]

Re: Wavelength of UV light for viewing fluorescence in diamo

neat pictures.
The common and cheap uv leds are around 385nm +/- 5.
The are often falsely advertised as being lower.
A good indication is cost... a 385nm wholesales for around 10c for the led when you buy in bulk, a true 365nm was in the 10-12 dollar range wholesale each just for the led last I checked.
So even in a $25 device odds are it will not have a 365nm led.

They have came down in price a little but still to high for a $25 device at retail:
http://www.mouser.com/ProductDetail/JKL-Components/BF350-UV1/?qs=sGAEpiMZZMt82OzCyDsLFDsWG3VmWP7Ji3NXlkfNgJ4%3d

Here is the one of the ones everyone uses:
http://www.mouser.com/ProductDetail/VCC/VAOL-5EUV8T4/?qs=sGAEpiMZZMs4quMj8r4lmkSLJrWtw8TTDkVmKqhWHqI%3d
I have seen better per 10000 prices on them.

 

[jstarfireb]

Re: Wavelength of UV light for viewing fluorescence in diamo

Nice! Do you have an auto-timer on your camera? Perhaps using the macro-setting plus auto-delay from hitting the button until the camera takes the snapshot would get a more in-focus image... No worries if not. They are cool as-is.

I think so (I do on my regular camera, but this is my Droid camera). The problem with the UV light is that it's such a tiny beam and it has to be shining directly on the diamond, with the camera oriented at just the right angle. I had to hold everything steady with my hands, so I'm not sure a self-timer would work. You're right - despite the focus and the way the color photographed, I think they're pretty cool.

Karl, that's interesting. The one I bought from Amazon calls itself 375nm, but from what you're saying, it's probably closer to 385. Not that it matters since I can see the blue perfectly well!

I don't actually see an effect of the fluor in daily sunlight, however. That's a bit of a bummer, but it was still a great stone for my upgrade (WF Expert Selection, only missed ACA because of the fluor).