No I didn't pay much, 15 dollars, but a lot of the repeat buyers of this site are the same names, probably wholesalers and resellers, why this seller is hard to find I don't know, but these are not cheap glass, they look amazing and the cuts are perfect looking, the crystal is clear of defects unless you inspect it internally by shining a bright light through it any then you can find the random tiny imp, but it sparkles like crazy from my overhead light from the many angles of the cuts, it looks and sparkles like any diamond I have seen.
This is not the first site that comes up on ebay when searching for man made/lab created diamonds, I first find many that are 500-1000% markup but the description is the same.
I have bought cheap glass and coated glass imitation stones from ebay and the cuts look almost rounded, but these are sharp and the refractive character is something you just have to see for yourself.
Cubic Zirconia, Lab Corundum items in Bangkok Pretty Gems store on eBay!
https://en.wikipedia.org/wiki/Corundum
These pics are not very good and my camera is just a 120 dollar cheapie marked down to 60 bucks when I bought it, but if I take my time later I can get some better pics.
I'm not unlocking any secrets of the universe here, this is just 15 dollars worth of fun.
With your safety glasses on you can see the laser beam split and make lines through the "gem" as you align it, it makes some pretty effects, safety glasses are a must.
With some fog you can get all the beams splitting out, I've posted pics with the smaller one splitting a beam before, I will put them at the bottom just for fun.
Old pics of small "gem"
Again this is just for kicks, everyone can take a little break sometimes and enjoy a bit of, hey that's pretty, it doesn't have to be important/serious to be fun.
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I missed your follow up question Alaskan, sorry about that.
All our off the shelf lenses such as G2, G7, G9 and the G-ball have a concave input and convex output.
My 25mm lens are 3 elements that I use with the raw diode output, yes there is some edge clipping but they slide zoom rather than thread as I use an expedient cardstock holder.
I understand focal length and have extended the burning range of our diodes far beyond what off the shelf lenses offer but I have a lot to learn about lens.
I am good at math and will be able to order by the numbers with AR coating once I understand better what is what numerically and the technical terminology and how it works, I know basics but lenses can get complex and efficiency is my goal because we already sacrifice beam quality for power with multi mode emitters.
I need a 100mm concave/convex to make a big G7 that grabs the diodes diverging output at a wider/longer position to focus energy at greater distance.
It is the most direct solution other than beam shaping first, but one lens changes how the next reacts....again I am still learning.
Now a relay lens expander like kobayashi used in his nubm44 that only lost 1/3 of the 6 watts and gave a good adjustable output would be nice, but I will go with cheap and easy for now.