You seem to have your gem ID methods in hand. Benzyl benzoate is not very toxic…in fact, it is
used as a topical medicine for scabies. That, of course, does not help when authorities are telling
you otherwise. It is readily available on ebay, and I think when I looked I did not see that they
listed the Philippines as a country that they do not ship to, so you should check there.
Looking into a faceted gemstone, you will see rainbows caused by refraction from the various
light sources about. The best way to view them would be with a single light source, say from a
small LED torch with a cap with a slit in it placed over the light. Usually I just look at whatever
rainbows I see from whatever light source there is. This shows me whether the rainbows are paired
(birefringence) or not. Sometimes they overlap, as in the case of quartz (small birefringence) and
topaz. You learn the patterns of the various gems after a while. A single light source would be
required to see the size of the circle of rainbows to estimate RI as Hannemann details.