A laminar assembly including a first optically opaque layer defining a plurality of through-holes, a second optically opaque layer, an optically transparent inner layer between the inner surface of the first optically opaque layer and the inner surface of the second optically opaque layer, and a preprinted layer proximate the outer surface of at least one of the first and second optically opaque layers. The plurality of through-holes is at least partially filled with material from the optically transparent inner layer, and light is visibly transmitted in a single direction through the plurality of through-holes. Unidirectional opacity watermarks defined by the plurality of through-holes in the laminar assembly provide advantageous anti-counterfeiting measures, and are easy to view and authenticate, yet difficult to simulate.