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A more concrete reason it's not true in this case: diamonds as engagement gifts from men to women are a recent cultural phenomenon. For most of human history this was not the case, and there were/are large cultures where the tradition is a dowry instead (more or less the reverse) or nothing at all.
It's not just impractical; it's impossible to know enough of the variables to derive one from the other.
In practice "evolutionary" explanations are constantly used to make something intuitively plausible for which there is no evidence sound scientific and convincing.