Essential oils, CO2s and absolutes are usually sold for use in small bottles. Commonly they are sold in 5ml, 10ml and 15ml bottle sizes. More expensive oils are sold in 2ml and 1 dram bottle sizes. These oils should be stored very carefully because they can easily get damaged by ultraviolet light and get deteriorated very fast at the blue end of the spectrum, as compared to red. They can lose their therapeutic benefits and deteriorate over time. For instance, citrus oil oxidizes and begins to lose aroma and its therapeutic properties; but not every essential oil loses its value, like sandalwood and patchouli oils.
You should always store essential oils in an amber colored bottle and if you are keeping the oil in a blue color bottle then keep it in a dark place, this is not so important for brown colored bottles. Dark glass bottles like amber or cobalt blue bottles can keep the sunrays out. Try and avoid purchasing any essential oil that comes in a clear bottle with a rubber dropper incorporated into the screw top cap because the highly concentrated oil has the capacity to turn the rubber bulb into gum. Never buy oils that are being sold in plastic bottles. There are some vendors who sell essential oils in aluminum bottles, but these bottles are acceptable if the interiors are lined. Always store the bottles in a dark and cool place because these oils can not take high temperatures and they evaporate quickly. Most of the oils come in a bottle that contains an “orifice reducer” which is a small, clear insert inside the bottle opening and acts as a dropper. You can easily tip the bottle and dispense the essential oil drop by drop. Remember to replace the cap quickly after use and make sure that the cap is closed tightly, when not in use.
Whichever essential oil you buy will last approximately for three years from the date of bottling. But if you provide excellent storage conditions then the oil can be stored for at least five years. There is dramatic reduction in the shelf life once the oils are diluted with carrier oils. A blend will be effective for approximately three to six months if you store it in an amber colored bottle in a cool place. With wheatgerm oil being added, the shelf life is about six to nine months. Remember to discard the oil if there is an alteration in the smell or when vegetable oil becomes rancid.
There are a few points that you need to keep in kind when you buy an essential oil:
o Buy oils in amber colored bottles
o Check for the date when it was bottled and how old it is
o The oils should not be kept in direct sunlight
o Check if all the essential oils are of the same price. This is an indication that you are being cheated. For instance, rosemary or lavender oil will be less expensive than rose oil.
o Check if the essential oil that you are buying is blended with any other carrier oil and if yes, then find out when it was diluted.