All our senses (sight, smell, sound, touch and taste) come into play. Here are a few pointers that might help you tell whether it's high quality Chocolate.
adapted: The chocolate and coffee bibble.
Based on Appearance:
Chocolate should be smooth, brilliantly shiny and pure mahogany-black in colour.
Based on Smell:
Chocolate should not smell excessively sweet.
Based on Sound:
Chocolate should be crisp and make a distinct "snap" when broken into two.
If the chocolate splinters, it is too dry; if it resists breaking, it is too waxy.
Based on Touch:
Chocolate with a high cacao butter content should quickly start to melt when held in the hand; this is a good sign. In the mouth, it should feel ultra smooth with no hint of graininess, and it should melt instantly.
Based on Taste:
Chocolate contains a kaleidoscope of flavours and aromas that continue to develop in the mouth. The basic flavours are bitterness with a hint of acidity, sweetness with a suggestion of sourness, and just a touch of saltiness, which helps release the aromas of cocoa, pineapple, banana, vanilla and cinnamon.
*Cacao - The botanical name and refers to the tree, the pods and at one the unfermented beans from the pods. The term is now used for beans that have been fermented.