Lets see, the RGB for dragon is :
255 51 230
Amethyst :
255 51 242
That's a minor enough difference to not be very detectable, and yes, this is intentional.
Also Amethyst is the more expensive of the two,
Dragon force: 18,000 tc
Amethyst force: 25,000 tc
And both of those items are sold out, so it matters even less.