A fragrance pyramid divides a scent into three tiers by evaporation speed: top notes are noticed in the first minutes, heart notes emerge over some hours, base notes stay longest. It is a simplified model, and many pyramids printed on sales pages describe images more than they list materials.
Three tiers on a sheet of paper
A perfume leaflet often prints a triangle split into three compartments. The top one lists a few words such as bergamot, pink pepper, green leaves. The middle lists rose, jasmine, iris. The bottom lists cedarwood, musk, vanilla. That figure is the fragrance pyramid, and its three compartments are the top, heart and base notes.
The short reading is this. Top notes are what is noticed right after spraying and fades first, from the first minutes up to an hour or two depending on strength. Heart notes appear as the top fades, carry the main character of the scent and last some hours. Base notes are the slowest to evaporate and remain for many hours, sometimes into the next day. Each word in the pyramid is called a note.
What needs adding is that a pyramid describes an intention, not a formula. A real bottle holds dozens to hundreds of materials; the leaflet prints a handful of words. Those words are chosen to evoke, and not every one corresponds to a material that can be bought.
Lê Mai's library has a pyramid builder that places essential oils in three tiers and shows their shares. What follows explains why the three tiers exist, and why a pyramid is worth reading slowly.
Evaporation decides the tier
A drop of essential oil on a blotter does not leave all at once. Small, light molecules with high vapour pressure leave the paper first; large, heavy ones stay. The pyramid sorts this difference into three compartments.
The top tier is usually monoterpenes and light esters. Limonene in citrus peel is the familiar example: it makes up most of sweet orange and grapefruit oil, and it is why the fresh orange smell fades quickly. The heart is flowers, spices and herbs, with molecules such as linalool, geraniol and eugenol. The base is woods, resins, mosses, musks and vanilla, where molecules are heavier and evaporate far more slowly.
The library's volatility chart lists how many hours each oil Lê Mai sells stays recognisable on a blotter at full strength, using figures from The Good Scents Company. Citrus is usually under a few dozen hours; woods and resins can exceed several hundred. The chart places 57 oils into three classes and marks which cells are estimates.
Blotter hours are not wear time on skin. Temperature, dilution, lot and the sensitivity of the nose all shift the figure. But the order is fairly stable: citrus leaves first, woods leave last. The pyramid rests on that order.
Is a note a material or an image
Some notes in a pyramid are names of real materials. Bergamot, lavender, vetiver and patchouli all have corresponding essential oils, and a bottle listing these words may contain those very oils. Other notes are names of an impression.
Lily of the valley, lilac and gardenia smell clearly on the plant but give no stable extract at an acceptable cost. In perfume their scent is rebuilt from combinations of molecules. A lily of the valley note on a pyramid is therefore a reconstruction, not a bottle of lily of the valley oil.
To rebuild such a flower, a perfumer can use the headspace technique: trapping the air around a living bloom on an adsorbent, then analysing it by GC-MS. Headspace yields no material for sale. The result is a data table, from which the scent is rebuilt with available molecules.
Further out are notes such as rain, sea air, warm skin, clean linen. A rain note is not a bottle of essential oil. It describes an effect the perfumer builds from many materials. The material closest to the idea is perhaps mitti attar, fired earth distilled into sandalwood oil in Kannauj, India; but a bottle listing a rain note need not contain it.
The note list on a box is best read as a sketch of an impression. It says what the perfumer wants the wearer to think of, not what is in the bottle. For composition, the only legally binding place is the INCI list, and there the whole fragrance usually appears under one word: parfum.
Pyramids without tiers
A pyramid assumes that a scent changes over time. Not every scent changes much. The classic Eau de Cologne puts almost everything in the top: citrus peel, orange blossom, rosemary, then a quick fade. Its pyramid is heavy above and thin below.
At the other end are scents built around a few base molecules. The pairing of ambroxide and Iso E Super, as the library records, underlies many minimalist woody amber perfumes. Both molecules belong to the base, so the scent keeps nearly one shape from spray to fade. Sales pages call this kind of scent linear.
Even in a formula with many tiers, the tiers overlap. Patchouli and vetiver are present from the heart to the end. Lavender has a bright top and a dry heart. The pyramid draws three separate compartments; in reality there is one continuous slope.
So the pyramid is most useful as a rough map: it shows direction, not the road. When placing a scent in a fragrance family, the heart and base matter more than the top, since nearly every family opens with citrus.
The pyramid as a blending lesson
The perfumer's word note comes from music. In 1857 Septimus Piesse published The Art of Perfumery, comparing odours with sounds and placing them in intervals like keys; later editions grew this into a staff of about fifty odours. It was a metaphor for arranging materials, not a measurement, but the word note stayed.
For someone blending, the pyramid is a starting frame. Blending manuals often give about 20 to 30 percent for the top, 40 to 50 percent for the heart and 25 to 35 percent for the base. Blending 101 and the library's pyramid builder start at 25, 45 and 30. This is a convention, not a rule.
The convention needs adjusting as soon as real materials come in. One drop of ylang ylang and one drop of sweet orange do not give the same amount of odour. Cinnamon, clove and vetiver need only a small share; citrus may need more to remain noticeable. The ratio on paper is a starting point; a blotter over hours and days shows which tier dominates.
The piece Three tiers of a scent goes further into these ratios; One blotter, three days records how a single blotter changes over time.
Building a pyramid
A pyramid can be built from blotters, with no leaflet at all. Dip three strips into three oils, write the name and time on each, then smell again after ten minutes, after two hours, after a day. A strip that has nearly lost its scent after two hours belongs to the top. A strip still clear after a day belongs to the base.
The same works with a bottle of perfume. Spray one strip, smell it at the same intervals, and note what is perceived at each point. That handwritten list often differs from the pyramid on the box: some printed notes cannot be found, some clear notes are not printed.
Smelling one scent for long tires the nose and reduces perception, an effect called olfactory fatigue. That is why evaluation is done in intervals, stepping away from the scent and returning. A handmade pyramid is more reliable when recorded over several short smellings.
The library's pyramid builder does the arithmetic: choose oils for each tier and split a total drop count by tier share. The drops there are ratios between oils in the blend, not the concentration on skin; the final concentration must stay below the limit listed on each oil's page.
A pyramid is a drawing of time.
Materials do not stay in their compartments.
A blotter records what the leaflet leaves out.