Some oils such as patchouli and sandalwood can improve. To avoid deterioration and protect the aromatic and therapeutic properties, your oils should be ideally kept in amber or cobalt blue bottles. Dark glass such as amber or cobalt helps to keep out sunlight which can hasten deterioration. Be leery of purchasing any oils sold in clear glass bottles. Run if you find an essential oil sold in a plastic bottle.
Some vendors sell oils in aluminum bottles.
It has been said that aluminum bottles are acceptable if the interior of the bottles are lined. Cobalt blue bottles are usually more expensive than amber colored bottles. Essential oils should also be stored in a cool, dark place. Wooden box used to store essential oils. Suitable boxes can be economically purchased unfinished from many craft stores and finished to suit the individual's taste.