precious
adj.adj. having great value because it is rare, expensive, or important to you. It can also describe someone who acts too delicate or behaves in a way that is annoying and fake.
adj. of great value, worth, or importance; often applied to materials like gold or stones. In a secondary, pejorative sense, it describes a person or style that is overly refined, affected, or fastidious.
The museum keeps its most precious jewels in a glass case.
She keeps her grandmother's old letters in a safe place because they are her most precious possessions.
While the ring was not worth much money, its sentimental value made it more precious to him than any luxury item he owned.
From Middle English precious, borrowed from Old French precios (“valuable, costly, precious, beloved, also affected, finical”), from Latin pretiōsus (“of great value, costly, dear, precious”), from pretium (“value, price”); see price.
Commonly used in the phrase 'precious metals' or 'precious stones'. When used pejoratively to mean 'affected', it usually follows a linking verb like 'be' or 'seem'.