Approx. 92.5 grade Silver caps are used, that means purity of silver is 92.5% approx, and wire used is of approx 30 grade i.e. purity of silver is approx 30% This is due to maintain softness and flexibility in silver wire since rigid wire cannot be twisted and turn.
Please also note, due to oxidation and exposure to air / moisture and to human body after wearing, the caps may turn black, hence we do not guarantee the shine of the same.
We cannot predict the time period in which it may turn black, it may vary from person to person.
Even pure silver exposed to air and moisture turns black on its own.