If the plating solutions ae hot, I would pre-warm the kunzite in warm
water, gradually raising the temp. Sudden heat changes will cause
spontaneous cleavage in kunzite, which is notorious for cleaving
easily. BTW, regardless of size, kunzite is a rather inexpensive
stone. Even in the very rare, very intense purple-pink colors, large
stones do not exceed $100/c. Pink ones are much less. Flawless
crystals weighing kilos are common.