Pearl and Moonstone are the modern gemstones for June, Alexandrite is the traditional gemstone, moonstone is the mystical gemstone, pearl is the ayurvedic gemstone with Opal being the alternate  gemstone .
        The soft, lustrous beauty of the pearl had led it to become a symbol of purity and virtue, and many are the virtues and legends attached to it. The Arabs called pearls "tears of the gods," and said they were formed by drops of rain falling into oyster shells. By the Chinese, pearls are regarded as the hidden soul of the oyster. And "margarithe," another name for this gem, means "child of light."
        Taken in milk, pearls were used to cure ulcers, while 6 grains in water sweetened with manna (ash tree sap) warded off the plague. Burnt pearl powder drunk in water stopped hemorrhages; inhaled, it cured headache. Oil of pearls was believed to fortify the nerves. Applying the oyster shell containing a pearl to the affected area healed leprosy and other skin diseases. The gem was considered beneficial for easing indigestion, curing hemorrhoids, and  counteracting poison. Nursing women took pearl concoctions to make their milk healthy and plentiful. Pearls also were essential toiletry articles, used to clean face and teeth.
        Although the pearl was a symbol of chastity, it was considered a potent aphrodisiac - and a mere ½ grain dose  would cure impotence. The Hindus deemed this gem appropriate as a wedding gift; the ceremonial piercing of a perfect ("virgin") pearl often formed a part of the nuptial ritual.
        Despite the many virtues of this gem, there were limitations and, even, risks attached to using it. In fact, defective pearls were believed to cause all manner of discomfort, from disgrace and misfortune to insanity, leprosy, and death.
        Like diamonds, pearls were credited with the ability to reproduce themselves. The quality was attributed to every ninth pearl, each of which was placed in a bottle with two grains of rice and left to breed. Pearl is one of the birthstones for the month of June. It is also the accepted anniversary gemstone for the 3rd and 30th years of marriage.

    Alexandrite is named for the former czar of Russia, Alexander II, and was first discovered in the Ural Mountains of Russia, supposedly on the day of his birth. Chromium gives alexandrite its color and while, in most minerals, a trace element like chromium would provide only one color to the mineral, in alexandrite it gives it two! Coloring agents are dependent on the wavelength of light and the chemical bonds in the crystal to determine the color that they will cause. An element like copper, in normal light, can cause a green color in malachite and a blue color in azurite, it all depends on the character of the chemical bonding. In a single specimen of alexandrite, the chromium is in such a balanced situation that the color of the specimen depends on the character of light that hits the crystal. If the light is natural sunlight or fluorescent light, the crystal will be green; however, if the light is incandescent light from a common indoor light bulb, then the crystal will appear red.
     Synthetic corundums spiked with trace elements that yeild an alexandrite-like color change are sold as alexandrite on the gemstone market. These stones have a red-violet, near-amethyst color in incandescent light and a blue-violet color in daylight. They are far cheaper than natural alexandrites, which are some of the rarest and most expensive of gemstones.
     Moonstone
         As its name suggests, this luminous stone was thought to have a strong link with the moon. In fact, the movement of light across its surface was believed to reflect the waxing and waning of that heavenly body. When   placed in the mouth during full moon, the moonstone enabled lovers to foretell the future of their relationship. Since another of the gem's attributes was to arouse the tender passions, this fortunetelling ability was very useful.
        The moonstone was used to ward off cancers and to make one invisible. Alchemists employed moonstone in   their efforts to change base metals to gold. Appropriately, moonstone protected its wearer from lunacy. For those born in June, the moonstone is one of their gems.