gem stones

what stone would one recomend if there are planets of opposite energies in 8 th house of capricorn asc.
if planets like sun saturn venus ketu and mercury all the present. if we take the rashi lord of 8 th. the sun would it not make the lagna weaker. and what about mercury ketu ( the kid has speech issues also )so we also ask mercury stone ketu would become weak and affect sun??
pls resolve this doubt..