Welcome to the delicate art of perfumery! To describe the absolute highest or most extreme degree of a quality—like the "purest" extract or "rarest" petal—Russian often uses a single-word morphological superlative.
The Standard Suffix "-ейш-"
To form this superlative for most adjectives, remove the standard ending (like -ый or -ий) and attach the suffix -ейш-, followed by the appropriate adjective ending.
For example, чистый (pure) becomes чистейший (purest), and новый (new) becomes новейший (newest).
| This is the purest essential extract. | Это чистейший эфирный экстракт. |
| There is an essence of rose in the newest composition. | В новейшей композиции есть эссенция розы. |
These superlatives often describe something as "extremely" or "most" beautiful, expressing an absolute peak even without a direct comparison.
| These expensive perfumes are sold in a most beautiful bottle. | Эти дорогие духи продаются в красивейшем флаконе. |
Consonant Mutation and "-айш-"
If the adjective's stem ends in a velar consonant like к, г, or х, that consonant mutates (for example, к changes to ч) and the suffix changes to -айш-.
A great example is the word тонкий (subtle, delicate). Because its stem ends in к, the consonant mutates to form тончайший (most delicate).
| A good perfumer has an extremely delicate sense of smell. | У хорошего парфюмера тончайшее обоняние. |
Similarly, the к in редкий (rare) mutates to ч to form редчайший (rarest).
| We gather the rarest petals for this essence. | Для этой эссенции мы собираем редчайшие лепестки. |
Declining Morphological Superlatives
Because these suffixes end in the hushing consonant ш, they decline exactly like adjectives such as хороший. They must match the noun they modify in gender, number, and case, adhering to standard spelling rules (for example, never write ю after ш; use у instead).
Notice how the superlative changes for the Accusative feminine when talking about a composition:
| This bottle contains the richest composition of essential extracts. | Этот флакон содержит богатейшую композицию эфирных экстрактов. |
And see how it takes the Dative neuter ending when referring to a perfumer's sense of smell:
| Let perfumers trust their extremely delicate sense of smell more, and not recipes. | Пусть парфюмеры больше доверяют своему тончайшему обонянию, а не рецептам. |