Swarovski bicone shape
Swarovski’s cutting machine allows for a technology-driven cut that creates a high refraction index in the crystals. They are known to be the highest quality glass crystal in the world. The machine is known to be so powerful and precise that it can create as many as 100 facets to mirror and bend light in various directions. It is then polished to perfection and you will notice that some of the bi-cone crystals will have a special coating such as AB (Aurora Borealis) that refracts light in a rainbow spectrum making them look beautifully elegant.
information sourced - https://www.isabellegracejewelry.com/blogs/igj/what-makes-a-swarovski-crystal-special