Mj plant turning a raspberry/puple color

I got this bagseed thats almost finished flowering prob got like a couple of weeks left to go before harvesting.. Its my second time growing it and seems to be turning a purplish/redish color mainly in the inside of the buds and could be seen in many calyxes, I believe its a sativa dom but could be mixed with indica.. My question is does anyone know of a sativa strain that turns purple starting with the calyxes? Also some of the veins on the leaves seem to be the same color..does anyone know why this happens? any help is appreciated

I have seen a sativa dom strain in the emerald triangle that would turn purple like the pic right before foxtailing not sure of the name however. I do know they were some OLD school genetics cause the grower was in his 70's and only grew from seed that he bred himself and had been doing it that way since the 60's.

CK