Chocolate created with beans from a particular area or region, i.e., single origin chocolate. It can either be a blend (e.g. Criollo and Forastero) or a single variety of beans, as long as the beans come from the one origin. The origin can be closely defined geographically, e.g. the island of Trinidad, or more broadly, e.g. the Caribbean.
The term was coined by Valrhona, which launched the first single origin bar in 1986, Guanaja 70%, a mix of Criollo and Trinitario beans, and defined the origin as South America. Their Jivara Lait milk bar is also from South American beans; their other Grand Cru bars come from Caribbean and Madagascan beans.
What Cluizel calls 1er [Premier] Cru chocolate, from specific plantations, is called Estate Grown by Valrhona.
To add to the confusion, in the wine industry, from which this terminology is taken, a Grand Cru wine is better-quality than a Premier Cru wine. But the reverse is true given these chocolate definitions: Cluizel