Little headcanon that larger gems take much longer to reform and emotions can also affect time. I figured pink might have done something a little childish/reckless if she did ever loose her form and so the shame/guilt might have increased the time it took her to reform.
If I called White Diamond correctly (always questionable) and you assume Blue is a kite shaped table cut, not something fancier, their styles also get progressively more complex over time- from Point, to Single Cut, to Double Cut- and mirror the actual evolution of diamonds.
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