Proper Astrological guidance is important before wearing the gemstones.

Once the gem fixed after consulting it should be properly tested as per ancient and modern norms. Because some times it is found that even though the gem is correct but the defective gem creates more problem.
Proper purification of gem is must, because the outer impurities must be removed.
The gem should be properly fixed in gold or in other metal through a skilled goldsmith. Some times defects come across the making.
The gem ring or locket must be worn on auspicious time or day (muhurt-).
On the day of wearing, gem ring or locket should be worshiped
The supreme God of all the gems is “Lord Shiva”. The basic mantra of gems is “! sava- r%naaiQaptyao iSavaaya nama:”.This mantra should be at least chanted 108 times ,by keeping the gem in front.
AS PER AYURVED
GEM
DISEASE
Ruby
Headache, urinary diseases, persistent fever, typhoid, acidity, stomachache because of acidity, heart disease, cholera, diarrhea, allergy, head scar, burning fever, persistent hiccups.
Pearl
Goiter, scrofula, acidic fever, vomiting, tuberculosis, stomachache because of acidity, hydroperitoneum, acidity, diarrhea, heart disease.
Coral
Acids in blood, ringworm, fistula, urinary diseases, rash and blisters all over the body, chronic lesions, fracture of bone, piles, dysentery, bleeding from any body part, fear of fire.
Emerald
Pain because of gases, tongue diseases, skin diseases like eczema, delirium, cough with vomiting, aggravation of all three Doshas.
Yellow Sapphire
Pain in head, nose, ears, tongue, eyes, heaviness in the body, oral diseases, breathing trouble, etc. problems due to the agitation of Jupiter.
Diamond
Nerve diseases, impotency, acidity, digestive system diseases, stomach diseases, intestinal pain, diarrhea, lungs diseases, tuberculosis, pneumonia etc.
Blue Sapphire
Tuberculosis, gases in stomach, unconsciousness, spleen diseases, muscle pain, paralysis, breathing related diseases, chronic fever, body pain due to gases, tremors in hands and feet, etc. problems occurring due to agitation of Saturn.
Zircon
Physical and mental diseases, madness etc. occurring due to agitation of Rahu.
Cat’s Eye
Anemia, gases in stomach
Tourmaline
Coordinator of the Six Rasas, Removes the Three Doshas, brings virility, cures anemia, stomach diseases, fever, breathing problems, tuberculosis, urinary diseases. It cures all major diseases. Highly nutritious, stimulates apetite, and hqas multiple curing qualities. Like diamond, tourmaline cures all the diseases.