Not only do you have an excellent quality loupe (and your loupe IS your best 'tester' for gemstones) but also a light to help look at inclusions AND a UV light (Long Wave). Some stones fluoresce under UV. Fluorescence is not 'diagnostic' but, as with most tests, it eliminates some possibilities, opens other possibilities, suggests which other tests to carry out, and that's how gemmologists identify stones.
Two interesting facts about UV light and diamonds.
1) Diamonds fluoresce randomly under UV light, so cannot 'identify' diamond using UV. However, BECAUSE the effect is random, if you have a few diamonds and they all fluoresce in exactly the same way, then they are unlikely to be diamond (on average you would expect one diamond in a cluster ring to fluoresce).
2) Many diamonds fluoresce blue under UV light and therefore if you are colour-grading they will appear better under UV light. Therefore, if the diamond fluoresces under this UV light, it will also fluoresce in daylight, and you may wish to be 'conservative' with your colour grade (a strongly-fluorescent diamond should be downgraded by two colours)