How to Convert Black Osmium to Blush Grey Osmium.

Hello,

I have 2 type of Osmium Sponge Powder with same purity 99.95%.
Can you tell me, what is the difference in both and how can i change Black to Bluish Grey.
Photo of Osmium attached.

Regards

Bhushan Aggarwal

baggarwal1303@gmail.com