I was browsing the Vermont Country Store catalog and found these items that looks interesting:

Colored Ice-Glo Sparkling Lites

Colored Ice-Glo Replacement Lites, 1 Assorted Box of 4 Expensive

White Ice-Glo Sparkling Lites

White Ice-Glo Replacement Lites, Box of 4 Expensive

Luckily, I have these General Electric Lighted Ice and General Electric Lighted Ice Bulbs in my collection

The ones i recall best from the 90s were with small "xmas light" incandescents (externally painted) with a sort of spikey ice crystal made of transparent plastic near the lamp base, which also forms the connector with which it plugs into the socket