Shiva Purana
श्वेतरक्ताः पीतकृष्णा वर्णाज्ञेयाः क्रमाद्बुधैः । स्वजातीयं नृभिर्धार्यं रुद्रा क्षं वर्णतः क्रमात् १२ ।
The colours of the four types of Rudrākṣas are respectively white, red, yellow and black. All people shall wear the Rudrākṣa of their own Varna.
english translation
zvetaraktAH pItakRSNA varNAjJeyAH kramAdbudhaiH । svajAtIyaM nRbhirdhAryaM rudrA kSaM varNataH kramAt 12 ।
hk transliteration by Sanscript