Makara rashi
Among the sixteen adornments, iron, steel and silver traditionally appear in payal and bichua — silver rather than gold, per the usual convention below the waist. That is a statement about materials and custom — silver below the waist, gold above it, stones set according to family tradition — rather than about what anyone ought to wear.
The chain from rashi to ruling graha to navaratna stone is classical and stable across texts. What does not follow from it is a recommendation. In actual practice, a Jyotishi choosing a gemstone looks at your lagna and whether the planet is a functional benefic for it, the planet’s dignity and house, and the dasha you are running. Two people with Capricorn rashi and different ascendants can reasonably be advised in opposite directions.
Blue Sapphire in particular is the stone the tradition treats most cautiously — practitioners who do prescribe it almost always recommend trial-wearing before committing, and it is also the stone most often sold under pressure. Treat any urgent recommendation to buy one as a reason for scepticism rather than haste.
Saturn also rules Aquarius, so the same stone and metals apply there.
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