stem and fan leaf stems are turning a dark purple

a little brown also in the middle of the fan leaves....does anyone know what this is a sign of?

I get purple stems but purple leaves ? Wud like to see a pic also, personaly i dont wory about the purple stem ting coz i got it last grow i av it this grow and probly av it on the next one, as long as she gives up is all that counts !!!

similar to mine, but mine is WAY stranger, in fact i just made a thread about it, i have a 5 day ols seedling whos stem is a nice greean, and the true leaves and coty's are a nice dark green, but heres the strange part, ONLY the underside of my leaves are dark purple, the tops are dark healthy green, and i have NO other signs of probs and am experianceing VERY rapid growth anyway, but the newest growth seems to be all purple instead of just the bottoms, im hopeing its just sum crazy rare phenotype i discovered in a seed i found in my carpet

so after doing some more research...i finally fed her some more and took the fan off of her.....and today she is doin much better.....i was just worried because i have had a lot of ppl tell me not to just up and add nutes....because it always could be a ph problem.....but i checked the ph again and it was 6.7 (soil) so i fed her some bloom nutes and put her into 12 and she up and healty again....maybe not full streng\th...but much better improvement!

Purple stems could mean the plant goes threw extrem temp changes ie. hot days cold nights. I have that with every grow I have done. Now purple leaves could be strain. Something mixed with say grape ape can produce purple leaves. Take kings kush(grape age x og kush) I have seen a lot of pics some have deep purple leaves some no purple exept on the buds. Hope that helps happy growing.