They’re definitely clay—paranoid is a clay/polymer composite related to celluloid/French Ivory that is compression molded for chips. They come in many weights and styles ranging from 5.5g bicycle tires (still really nice) to square-edged 8g-ish chips. The ones in the ad are the 8.0g ones that kick ass! Great sound, and in the stacking department both Paulsons and ASM/CPC actually get soundly outclassed by a good set of paranoids. No joke! Paulsons and ASMs are superior in several other ways and ultimately better chips. But when considering a set of Paulsons or other serious chips, 8g paranoids are good enough to be both worthy and welcome in the discussion.
Value? For top end paranoids everybody seems to ask around $1/chip, but they never seem to sell at that price. At 50c/chip, small lots of the 9g ones are often gone in a flash.