Bottle: The main glass container.
Orifice-Reducer Insert (Dropper Cap): A plastic insert that fits inside the neck of the bottle. It has a tiny hole that controls the flow of oil, allowing you to dispense it drop-by-drop and preventing spills.
Cap (or Closure): Screws on over the orifice reducer to create an airtight seal. Caps are often made of phenolic resin (which is chemically resistant) or plastic.
Euro Dropper Assembly: An alternative to the orifice reducer. It consists of a glass pipette, a rubber bulb, and a plastic cap. It's better for creating custom blends and measuring precise amounts, but is less leak-proof for travel.
Label: Crucial for identifying the oil and its details (e.g., botanical name, expiration date, safety warnings).


This is the most critical feature.
Amber (Brown): The most common color. It blocks over 90% of UV and visible light, providing excellent protection against photodegradation.
Cobalt Blue: Also offers very good UV protection and is often used for aesthetic appeal.
Green: Provides good protection, though slightly less than amber or cobalt blue.
Clear Glass: Generally avoided. If used, the oil must be stored in a completely dark place. Clear bottles are sometimes used for display or short-term storage of less sensitive oils.
Why glass? Glass is non-porous and chemically inert. It will not react with the potent essential oils, ensuring the oil remains pure and uncontaminated.