This isn't actually solid Heartstone, it's Heartstone-plated. Kind of a letdown, really.
Heartstone Block price in Growtopia: sells for about 10/WL, buyers pay about 30/WL (median of 112 offers from community Discords, past 30 days). Live price chart and the latest buy and sell offers.
Recently sold at: POBS, EVENTV3, PUPUZ, AZMET, TOMOMI