different mint colours for 5 rupee coin

as u can see in the picture below, the 5 rupee coin seems to have different colours

the one on the left is from 2017 Noida mint and appears to be yellow
the one on the right is from 2015 Hyderabad mint and appears to be gray

both coin have the right diameter and thickness and both weigh 6 g


both also appear to have mint luster

can someone please tell me about them?

(p.s these are not just one odd coins i found , every coin i have found in circulation also appear to be either yellow or gray
thus the chances of one of them to be counterfeited is very unlikely)

Better quality photos please.

I hope that the picture is better