When Bismuth was first mentioned, it was said that she and Amethyst became friends as soon as Bismuth was built.
Later, Bismuth was seen talking to her best friend, Topaz, about how much she wanted to go to Sodor, but she wasn't aloud. Topaz told her to take some gems to Sodor anyways, so Bismuth took the train that Amethyst was going to. However, on the way to Sodor, Diamond, Jasper, Aquamarine, Holly Blue, and Malachite started playing tricks, and Bismuth ended up having an accident.
Bismuth is friendly, boisterous, fierce, determined, empathetic, and emotive. She is not afraid to speak and act her mind. She also cares deeply for her friends. She is also slightly naive, as she is the youngest engine on Crystal Island.
Like the other Crystal Island engines, Bismuth has no specific basis, although she resembles a BR Standard Class 9F with 2-10-2 wheel arrangement and a Fowler tender
Bismuth is painted lavender with rainbow colored lining and wheels. She also has a dark purple cylinder and dome. She has pink tender lining and a pink bufferbeam/footplate. She has her number in black inside a pink star on her tender, along with her rainbow colored gemstone.
There are some differences between her original design and her current design:
Her original design did not feature her gemstone.
Her current design is a lighter lavender and a darker pink
The blue and green are switched on her current design