Monique said:
How can someone interested in physics not like light-reflecting crystals?
I love crystals. I have mined my own tourmalines and beryls right here in Maine and have bartered and bought materials from all over the world. Every female relative that I have (down to the 2nd cousin level and more distant in some cases) has at least one piece of jewelry featuring gemstones that I have faceted. My faceting machine is really not equipped to facet diamonds, but that's OK because the market is pretty much throttled by entities that want to keep diamonds as expensive as possible.
I have faceted and given away stones that are much, much rarer than diamonds, including beautiful pastel sapphires from Yogo Gulch, tsavorite mined in Tsavo national park in Kenya, Tanzanite, emerald, rubies, etc, etc.
A few years ago, a nice young lady (who has 2 of my stones) asked my opinion of her diamond engagement ring, and I said "it's very nice." to which she answered "No, I want you to look at it and tell me what you think". I went back in the house and got a 10X loupe and a lump of modeling clay to hold the ring steady while I examined the stone. The diamond had several voids and hair-thin "tunnels" leading to them. She had a stone that was perhaps a bit over 1/2 carat that looked a little "soft" because the refraction was broken up by those uneven voids left after inclusions had been vaporized with a laser. Diamonds are a scam backed by one of the most effective marketing campaigns in history.
Crappy worked-over diamonds are all over the US market, as are inky sapphires, and pink sapphires being marketed as "rubies". The gem market in the US is very dishonest, with jewelers over-grading stones that would not warrant a second glance on the Asian market.
At a dinner after a business meeting, I was seated next to my company's VP of sales (international company), and I said to him "What a beautiful sapphire!" He had a heavy gold ring with an irregular cabochon sapphire that must have been close to 10 carats. He smiled and immediately took off the ring and handed it to me so I could look at it more closely. The stone was a beautiful rich blue with no visible inclusions or silk. He explained that his parents escaped China in advance of the revolution, and carried as much wealth as possible with them in the form of precious stones. The guy was carrying a fortune around on his finger, and he seemed genuinely surprised and pleased that an American would recognize that.