Inestimabile vs. prezioso

The Italian words 'inestimabile' and 'prezioso' both convey the idea of high value, but they have subtle differences in usage and connotation.

Inestimabile

'Inestimabile' means invaluable or priceless, emphasizing that something's worth is so great it cannot be calculated or estimated.
L'aiuto di mia nonna è inestimabile.
(My grandmother's help is invaluable.)
Questa collezione d'arte ha un valore inestimabile.
(This art collection has inestimable value.)
L'esperienza acquisita durante il viaggio è inestimabile.
(The experience gained during the trip is priceless.)

Prezioso

'Prezioso' means precious or valuable, indicating something of high worth, but not necessarily beyond estimation.
Questo anello è molto prezioso per me.
(This ring is very precious to me.)
Il tempo è un bene prezioso.
(Time is a valuable commodity.)
Ha ricevuto un prezioso consiglio dal suo mentore.
(He received valuable advice from his mentor.)

Summary

While 'inestimabile' is used for things of such high value that they cannot be measured or estimated, 'prezioso' describes items or concepts that are highly valuable but not necessarily beyond price. 'Inestimabile' is often used for abstract concepts or unique items, while 'prezioso' can be applied to a wider range of valuable things, both tangible and intangible.