Hi Isaac Start with a known. Do you have some blue glass or red glass that you can practice with? Both should give some kind of spectrum just to at least give you one to see. Next try a known stone- rubies usually give a spectrum if there's any stone that I could point to. Garnets are another that often give great spectra-though not often textbook. I hope this helps.

Starla Turner Hi Starla, I've managed to get some strong absorption lines with some lovely unheated Mozambique rubies i have. These were much easier than the stones i was previously trying with. I've also managed to identify the sodium D line in both my spectroscopes which i'm really happy about! However i still really struggle to get any clear absorption lines for alot of my other stones - particularly emeralds. Al ot of my emeralds are quite light in color but i still think there should be something to see. I read something on the gemologyproject page which says that 'emerald is known to show different absorption spectra along the ordinary and the extraordinary vibrational directions'. Is this referring to the optical axis in birefringent stones? and do you have any tips for finding absorption lines in lighter colored stones like emeralds? Once again, thank you so much for your help, your videos are grade! i'd love to see more!

Hi Alex, sometimes the two colours will be a lighter and dark version of the same colour, just make sure you aren't looking over some colour zoning in the stone. Yes, this is absolutely a way to orient rough. Generally, the direction of single refraction, where you will only see one colour in a doubly refractive stone, gives the purest colour. In tanzanite or iolite, you do want the purple or blue colours to exit through the table so you cut accordingly, bearing in mind the cleavage directions the stone. In tourmaline, looking down the crystal, the stone absorbs almost all colour, it just looks black when you look at the end, if you want your stone colour to be darker, you cut the table in this direction but if the crystal is already quite dark then you cut the table parallel to the length of the crystal.

I really appreciate your help Starla, Do you have any books or any other source in your mined regarding stone orientation or similar subject so I can study all stones in rough before cutting to make sure I do not make a mistake in orientation ?

Start with a stone that does have an easy to see spectrum, like your ruby. Get really strong back lighting and look through the part of the stone where you see the brightest glint of light. Move your dichroscope along the stone and you may see different lines at different times. Many people like the reflected light, where you shine the light on the stone and put your spectroscope at the equal but opposite direction to catch the light that is bounced off the stone. get the spectroscope close to the stone to catch the reflected light. Remember there is never an always in gemology, many many stones do not give up a good spectrum. Typically, garnets and ruby, and the synthetic spinels give the best spectrums. You could even check the spectrum of olive oil coming out of a transparent bottle if you can get enough light, or try green class. A lot of transparent materials will give you a spectrum, once you start to see how the light angles work it gets easier to do on small pieces like gemstones. Good luck!

@@starlaturner thanks very much for your prompt reply. I will try the techniques you suggest.

I don't sell equipment, you can go to GIA.edu to get it or Kassoy.

Starla Turner I'm from Morocco it's far