Quoted By:
>Gold and Silver are metals
>Crystal, the gemstone
>Diamond and Pearl are gemstones, there's a legendary that would fit the Opal gemstone really well
>Platinum, the metal
>Black and White meet in the middle at Grey
>Black and White 2
>XY even have a logo ready to use for Z
>Sun and Moon
The only one with actual logic behind it is Emerald and Japan's Blue version, which America didn't even get.
