Stripping a normal item gives shards repeatedly.

[sinful pumice]

Inert Diamond + Ancient Coal + normal item(no sparkle) = shard every time.

every inert diamond here is a shard if exploited

I don't need to exploit it, I'm lacking BiS sparkles. Enough farming and you get more than enough shards and stones

[finite trout]

Can confirm this. Every time you get a shard no matter what is put in there.