Cala Rossa, Ortigia

What Seaglassmap found here

Ortigia is the old island heart of Syracuse, lived on for something like 2,700 years, and Cala Rossa is the little pebble cove on its eastern shore. Collectors who work it come back with almost the whole range of colours in a single visit. Watch for the pieces that read as black in your hand and turn deep violet against the light. That is manganese glass, made colourless when it was blown and slowly turned purple by a century of sun.