THCa Diamonds for sale. If you want to buy THCa diamond crystalline from a source you can trust, you’ve come to the right place. All of our THCa diamonds are 2018 Farm Bill compliant. None of our products exceed the .3% THC threshold as required by article 10113 of the US Farm Bill. As a result, our crystalline products are legal to purchase. Our inventory is in HIGH demand as you would imagine. For inventory enquiries please contact us.