You've described it well ["Feels like plastic"] and with an additional note of color and rounded edge... along with a 'recessed center' or 'raised edge' should call it.

"Several different types of chips used in South America, Asia [and Europe] are made of various types of material. It's suggested the collector indicate type of material and note shape and color in describing this type of chip." Note from Guide to Collecting Gaming Checks and Chips by Howdy Herz.