The olfactory pyramid, also known as the fragrance pyramid or scent pyramid, is a method used by perfumers to classify and describe the various notes and ingredients in a fragrance. The pyramid is divided into three main layers, each representing a different group of scents. These layers are known as the top notes, middle notes, and base notes.
Top Notes: The top notes are the initial scents that are perceived when a fragrance is first applied. They are the most volatile and evaporate quickly. As a result, they are usually made up of light, fresh, and citrusy scents that are designed to provide an immediate burst of fragrance. Common top notes include bergamot, lemon, orange, and grapefruit.
Middle Notes: The middle notes are also referred to as the heart notes of a fragrance. These scents emerge after the top notes have dissipated, usually within 15-30 minutes of application. They are often more complex and enduring than top notes and provide the main body of the fragrance. Middle notes are usually floral or spicy, and common scents include jasmine, rose, lavender, and cinnamon.
Base Notes: The base notes are the final scents to emerge in a fragrance, and they can last for hours after the top and middle notes have dissipated. Base notes are usually rich, deep, and earthy and provide the foundation for the fragrance. Common base notes include musk, vanilla, sandalwood, and patchouli.
It's worth noting that the olfactive pyramid is not a strict rulebook for fragrance composition, and some fragrances may not fit neatly into these categories. However, the pyramid is a useful tool for understanding the structure of a fragrance and how different notes interact to create a unique scent.