The engagement ring
Worn on the fourth finger of the left hand because the Romans believed a vein ran from it straight to the heart. There is no such vein — the anatomy is the same as every other finger. The custom survived the biology, which is quite a good argument for customs.
The diamond part is younger than most people think. Until a 1930s advertising campaign, coloured stones were at least as common, and a sapphire or a garnet is not a compromise on anything except marketing.
The wedding band
A circle with no join, no beginning and no end. Plain bands became the norm in Britain during the Second World War, when metal was rationed and ornament was unpatriotic — austerity turned into taste and never turned back.
Worn inside the engagement ring, closest to the heart, in most of Britain. In much of Europe it goes on the right hand. Both are correct; neither is a rule.
The signet ring
The oldest working jewellery there is. A signet was a tool — you pressed it into wax and it was your signature, which is why the engraving is reversed and why they were worn on the little finger of the hand you did not write with.
Still the piece people most often bring back to have re-cut for the next person in the family. The metal outlasts several sets of initials.
The eternity ring
Stones set all the way round, given to mark something that has already lasted — a first child, a tenth anniversary. Full eternity rings cannot be resized, which is a genuinely important thing to know before buying one.
Half-eternity is the practical choice: the same look from above, resizable, and the plain half sits more comfortably against a wedding band.
Memorial jewellery
The Victorians wore jet, and hair, and photographs in lockets, and it was ordinary rather than morbid. The modern version is usually a remodelled stone: something that belonged to someone, made wearable again.
This is the most common reason a stranger emails this studio, and the work she takes the most care over.
What to have engraved
A date, initials, or four or five words. Not a sentence — a 6mm band gives you about eighteen characters inside before the letters have to shrink past reading size.
Engraving is inside for something private and outside for something declared. She will ask which, and there is no wrong answer.