Insure it the week it arrives
An engagement ring is often the most valuable object its owner carries daily, and standard home-contents policies cap jewelry payouts at low limits. In the US, dedicated jewelry insurers (or a 'scheduled personal property' rider on home/renters insurance) cover loss, theft and damage for roughly 1–2% of the ring's value per year. In India, jewelry floater policies and bank-locker policies from major general insurers serve the same role. Either way the insurer will ask for exactly two documents: the purchase invoice and the diamond certificate — keep both filed digitally.
The three times to always take it off
Gym and weights (bars bend prongs and scratch bands), swimming (cold water shrinks fingers — pools and oceans eat rings — and chlorine attacks gold alloys), and any work with grit, dough or chemicals. Develop one habit: a single fixed dish at home where the ring always goes. Most lost rings are not stolen; they are set down somewhere unusual.
Cleaning at home: two minutes a month
Diamonds attract grease — a week of hand cream leaves a film that kills sparkle. Soak the ring ten minutes in warm water with a drop of dish soap, brush gently with a soft toothbrush (especially under the stone, where grime collects in the basket), rinse and pat dry. Avoid toothpaste, baking soda and 'jewelry dip' solutions on rings with pavé — abrasives scratch gold and harsh dips can loosen small stones.
The professional schedule
Once a year, have a jeweler check the prongs (worn or lifted prong tips are how center stones are lost), the pavé seats, and re-polish if desired. White gold benefits from rhodium re-plating every one to three years depending on wear. If you ever feel the stone move or hear it rattle when you tap the ring near your ear — stop wearing it and have it tightened that week; a loose stone is days, not months, from falling out.
Resizing realities
Fingers change with seasons, age and life. Plain and half-pavé bands resize easily up or down about two sizes; full-eternity bands and tension settings often cannot be resized at all and must be remade. This is one quiet argument for half-pavé over full — and for getting sizing right at order time, measured at day's end on the actual wearing hand.