Sometimes the only message that people wish to convey when presenting someone with a gift is that it was meant to be special and personal. It is common to see engravings that have nothing else in them other than relationship terms: mother, father, sister, brother etc. If this is what you want, but would still want the engraving to be a little bit more classy use the language best suited for the job, Latin. Here is a quick rundown of the words you can use. All the terms are in the correct cases. All it takes is just to have them engraved!
Uxori meae - To my wife
Uxori meae carissimae - To my dearest wife
Marito meo - To my husband
Marito meo carissimo - To my dearest husband
Amico meo - To my friend (masc.)
Amicae meae - To my friend (fem.)
Amicis meis - To my friends
Matri meae - To my mother
Patri meo - To my father
Fratri meo - To my brother
Sorori meae - To my sister
Filiis meis - To my sons (to my daughters)
Uxori et filiis meis - To my wife and my children
Marito et filiis meis - To my husband and my children
Filio meo - To my son
Filiae meae - To my daughter
Avo meo - To my grandfather
Aviae meae - To my grandmother
Transcribing modern names into Latin is a whole different story, but the good news is that you don’t really need to have that for your engraved message.