I’m sure we all remember when Topaz shards were utterly overpowered only to be nerfed so hard as to be all but abandoned outside secondary crit chance. Since then DE have said they follow the same rules Calibans lethal progeny ability, this howerver is incorrect and Topaz shards appear to be even more limited. They in fact seem to obey the following 2 rules.

• Overshields cannot be generated.
• Shields cannot be generated during ANY kind of recharge delay.

The second point is important because any recharge delay includes the brief one every time you’r hit, even if you still have shields and haven’t shield gated. The result is that Topaz shards cannot generate any shields while under fire.

This in my opinion is likely an oversight as it renders them utterly useless since their only potential utility is when you’re not in combat yet still able to kill enemies with a blast, a situation not only incredibly rare but also one where shields regenerate on their own anyway.