they are mostly just stars the five pointed ones are the most common , those in the Stars and Stripes are as such for example and so are those in the EU Flag.
There are those related though , Skin Diamond and Asphyxia Noir share a special relationship and they both have two stars on both hands at the base of the thumbs one a little bit bigger than the other.
They never shared the meaning of these , I think it's private but they are most likely related

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