For Countless centuries, the cultures of India and South-East Asia have revered the beautiful nine-gem talisman known as 'Nava-Ratna'. Combining the gemstones representing each of nine planets in sidereal astrology, the 'Nava-Ratna' is esteemed by ancient tradition as a bringer of good fortune through its favourable influence on the planetary energies.
The most well-known design places a ruby, representing the sun, in the center encircled by eight other planetary gem-stones.  Diamond for Venus, pearl for Moon, coral for Mars, hessonite for Rahu, blue sapphire for Saturn, cat's eye for Ketu, yellow sapphire for Jupiter and emerald for Mercury.
Sapta-Ratna, the seven jewels talisman, combines the gem which correspond to the planets ruling the seven days of the week.  Every day of the week is governed over by a specific planet. In English we must simply examine the Anglo-saxon origin of the names of the days to see the correspondence, Sunday(sun), Monday(moon), Saturday(Saturn) remains same. Tuesday(Mars), Wednesday(Mercury),  Thursday(Jupiter), Friday(Venus).

The sapta-ratna should be used as seven different rings or pendants to worn successively on each corresponding day of the week. This practise is still popular in India, especially among astrologers, royal families and wealthy people.

Pancha-Ratna combines the gemstones which represent a balance of five material elements. Thus earth is represented by the green in emerald, water by blue in sapphire,  fire by red in ruby, air by the yellow in topaz, space by the absence of color in diamond.  Another combination of the five gems has been described as gold for earth, pearl for water, ruby for fire, blue sapphire for air, and diamond for space.
The Tri-Ratna is a talisman believed to balance the three constituents of one's material body, crudely translated as marrow, mucus and air. These are represented by three primary cosmic colors in nature - red, yellow and blue, or ruby, red coral and yellow sapphire.
Bona fide Vedic reference regarding the Nine Planetary Gems, The quote attributed in sanskrit in 'Brihat Jatak'

Manikyam dinanayaksya vimalam muktaphalam, shitagoh maheyasya cha vidruman  marakatam saumyasya-garutmakam, devejyasya cha pushparagam sura-achryasya vajram shaneh nilam, nirmalamanyayoshcha gadite  gomedh-vaiduryake.

Translation: The Sun's gem is pure ruby, Moon is (natural) pearl, Mars is red coral, Mercury is emerald, Jupiter is yellow sapphire, Venus is diamond, Saturn is blue sapphire, Rahu is hessonite, and ketu is cat's eye.