Mojssanite (sp?) and zirconium stones have those properties as well, and cost much less. Some other gem stones are very hard to distinguish from diamonds without specific tools.
Does your sister have a preference for diamonds over finely cut zirconium (or even glass)? It’s likely not as simple as that, even if you and her try to rationalize it that way.
I nor her have any specific preference for diamonds. I only explained why she, and many people, like them: it’s as dumbly simply as “sparkle, sparkle”.
This is literally what my sister responded with when I asked her why she liked diamonds so much:
https://pics.me.me/hello-everybody-sparkle-sparkle-15208126....
Bitcoins aren’t pretty. Sparkling, finely cut specific rocks are. Sometimes it’s as simple as that.