First of all, cleanse this item. There are three ways I suggest.
Sea Salt Bath.
Wash or bury this with sea water or seal salt allow it to stay in it for like 10 mins. Then take it.
Most basics. Hold the stones to moon light and visualise black energy leaving as a smoke and then going to earth where it becomes normal energy again.
Most people don't like this. You pass the stones from a white candles fire several times. Be careful because you might damage the stone.
After you cleansed them. Research what you have to do. Here is the day correspondances.
Gemstones: Quartz crystal, diamond, amber, carnelian
Associations: Agriculture, beauty, hope, victory, self-expression and creativity
Gemstones: Pearl, opal, moonstone
Associations: Childbearing and family life, purity and virginity, healing, wisdom.
Gemstones: Garnets, ruby
Associations: War and conflict, enemies,marriage and protection
Gemstones: Adventurine, agate
Associations: Business and job-related issues, communication, loss and debt, traveling and journeys
Gemstones: Turquoise, amethyst, lapis lazuli
Associations: Honor and family loyalty, harvests, clothing and riches, fealty
Gemstones: Coral, emerald, rose quartz
Associations: Family life and fertility, sexuality, harmony, friendship, growth
Gemstones: Apache tear, obsidian, hematite
Associations: Agriculture and creativity, fortune and hope, protection and banishment of negativity
After the day you chose, moon phase must be a waxing moon, which will be soon. Doing the exrecise written by Drakelius while burning a colorful candle that has to do something about your intention will enchant this object. :)
I would write color correspondances too... But it would be too long, so just search wicca colors and you will see a lot of it. ^^
Hope I help!