Why can a product sold as "ice silk" feel cool even if it contains no silkworm silk?

Answer: Cool touch is engineerable

Cool touch is engineerable ✓ — Correct. The word silk in a marketing label does not guarantee silkworm fiber. Cool touch can be engineered through fiber type, yarn shape, fabric structure, moisture movement, and surface heat exchange. That is why a rayon or polyester blend may feel cool for real, while still not being silk in the biological sense.

Natural fiber is required — Natural origin is not required for cool touch. Some synthetic or regenerated fibers can be shaped, filled, or blended to change heat flow and moisture movement. The surprise is that a petroleum-based or cellulose-regenerated fabric may beat a natural one on one narrow sensation while losing on other values such as biodegradability or hand feel.

Labels prove fiber source — Labels are clues, not proof of fiber source. Real silk has a biological source and measurable properties, while ice-silk is often a trade description for a cool-feeling blend. The honest test is mechanism: what fiber and construction move heat or moisture, not whether the label borrows the prestige of silk.