Fuck your ice
I rock rubies, amethyst

from Nas (Ft. Large Professor) – Loco-Motive Lyrics on Rap Genius

Meaning

While ya’ll rock small/common amounts of ice, Nas is rocking all types of jewelry like rubies and amethysts.

An amethyst is a violet variety of quartz often used in jewelry:

A ruby is a pink to blood-red colored gemstone:

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