CJR, while I would still pursue the polical route as it will eventually work, IMO in order to (as you say) get the ball rolling legally, Crystallex must advise Venezuela that they are in breach of the agreement.

"If a dispute has not been settled amicably within a period of six months from the date on which it was initiated, it may be submitted by the investor to arbitration in accordance with paragraph (4). For the purposes of this paragraph; a dispute is considered to be initiated when the investor of one Contracting Party has delivered notice in writing to the other Contracting Party alleging that a measure taken or not taken by the latter Contracting Party is in breach of this Agreement, and that the investor or an enterprise owned or controlled directly or indirectly by the investor has incurred loss or damage by reason of, or arising out of, that breach. Bilateral Trade Treaty Art. XII, § 2.

BUT there is no rush (other than financially related issues), as Crystallex has three years from the date of the breach to initiate action. Bilateral Trade Treaty Art. XII, § 3 §§ d.