Matsya Purana — Ritual Procedure and Merit of Donating the Ratnācala
पूर्वेण वज्रगोमेदैर् दक्षिणेनेन्द्रनीलकैः पद्मरागयुतः कार्यो विद्वद्भिर्गन्धमादनः //
pūrveṇa vajragomedair dakṣiṇenendranīlakaiḥ padmarāgayutaḥ kāryo vidvadbhirgandhamādanaḥ //
The wise should fashion (or delineate) Gandhamādana so that on its eastern side are diamond and gomeda gems, on its southern side Indranīla (blue sapphire), and it is furnished with padmarāga (ruby).
This verse is not about Pralaya; it gives a Vāstu-like directional prescription for Gandhamādana, emphasizing auspicious materials rather than cosmic dissolution.
It reflects the broader Purāṇic ideal that rulers and householders should commission sacred spaces correctly—using learned experts and auspicious directional arrangements to support prosperity, legitimacy, and ritual order.
It encodes a directional-material rule: specific gemstones are assigned to specific directions (east and south), a hallmark of Vāstu/ritual design where orientation and substances are chosen to enhance auspiciousness.