The ring is the easy part

Give yourself eight weeks. A custom setting with a stone you picked out yourself runs about that long from the first appointment to the box in your pocket, and if you want it for a specific date, you start two months early and not two weeks. Ready-made rings off the case are faster. Sizing still takes a few days at most shops.

That's the logistics. The logistics are the least of it.

Certainty isn't the thing you're waiting for

Men stall for years waiting to feel sure, as if one morning the fog lifts and a voice confirms it. That morning doesn't come. What you get instead is evidence, and evidence is better, because you can actually examine it.

So examine it. Not how you feel around her at her best. How she behaves at her worst. How she talks about her mother when her mother has been difficult. Whether she's kind to people who can do nothing for her, including the twenty-year-old taking her order. Whether she keeps small promises without being reminded. Whether she apologises without a lawyer's caveat attached to it.

And look at yourself with the same eye, because she's doing the same maths. Marriage doesn't reward the man who found the right woman. It rewards the man who became the kind of husband a reasonable woman would want to stay married to.

One more piece of evidence, and it's the one people skip: watch how she treats you when you fail. Lose a job, botch a decision, get something badly wrong. If she's decent to you in that week, you've learned more than a year of good weekends taught you.

Four conversations, before you spend a dollar

You should be able to sit at a kitchen table and get through all of these without either of you leaving the room.

Money, with real numbers. Not "I've got some student loans." The balance. The interest rate. What she earns, what you earn, what each of you carries on a card. If you can't ask her what she owes, you're not ready to ask her the other question. This is also where you find out whether she thinks debt is normal and whether you think it's a moral failing, which is a fight you'd rather have now.

Children. How many, roughly when, and what happens to two careers when the first one arrives. "We'll figure it out" isn't an answer. Somebody's job changes shape. Decide now which of you is expecting that to be them.

Faith, as practice and not as a label. Lots of couples discover after the wedding that "I'm a Christian" meant Christmas and Easter to one of them and a Sunday-morning commitment to the other. Ask what she actually wants the rhythm of a household to be. Ask what she'd want for a child at eight years old.

Geography and parents. Whose city. Whose family you end up ten minutes from. And the hard one nobody raises at 27: if her father has a stroke at 62, what do you do, and where does he live.

How you argue is the data

Every couple fights. The question is what the fight looks like from the inside.

Does it stay on the subject, or does it become a tour of every past offense. Does she shut down for two days. Do you. Does either of you use the word "always." Can one of you say "you're right, that was mine" while still annoyed.

If you've never had a real disagreement, that's not a green light. That's missing information. Some couples avoid conflict so thoroughly that the first genuine argument happens in year two of the marriage, and neither of them has any idea how to do it.

A concession, because it's honest: length of courtship isn't the variable people think it is. Some couples know at seven months and are still solid at thirty years. Others date for five years and divorce in eighteen months. Time doesn't prove anything on its own. What it buys you is more chances to see the thing you need to see. If you've already seen it, more months won't help.

What she actually wants on her hand

Surprise her with the timing. Don't surprise her with the ring.

Her sister or her closest friend knows the shape she likes, whether she wants yellow gold or white, whether she'd be horrified by a halo. Use them. Screenshots exist for a reason. If you'd rather ask her directly, that's also fine, and plenty of women are relieved to be asked. The romance isn't in the ambush.

Practical details that go wrong:

• Shape beats size. She has an opinion about oval versus round and no opinion at all about the difference between 1.0 and 1.2 carats.
• Match her other jewelry. If everything she owns is yellow gold, don't buy platinum because it sounds expensive.
• Sizing. Borrow a ring she wears on the right ring finger and take it in, but tell the jeweller which finger it's from. Err slightly large. Sizing down is usually straightforward. Sizing up has limits, and a full eternity band with stones all the way round often can't be resized at all.

The four Cs, ranked by what a person can see

Cut first, and it isn't close. A well-cut stone throws light across a room. A poorly cut one of the same weight looks like glass in a kitchen. Everything else is secondary to this.

Color and clarity next, and only to a point. Nobody standing three feet away can tell an eye-clean SI1 from a flawless stone, and you're paying a great deal for the grades above what human eyes resolve. Ask for eye-clean. Look at the stone yourself in daylight, not under the shop's spotlights, which are engineered to flatter.

Carat last. Weight is the number people quote and the one that matters least to how it looks.

On lab-grown versus mined: a lab-grown diamond is the same material, and it costs a fraction of the natural stone at the same specifications. The gap is large enough to change what you can afford by a tier or two. Resale on both is poor, so don't buy either as an investment. Buy natural if she'd want natural, or if there's family sentiment attached. Buy lab-grown if you'd rather put the difference into a house deposit. Neither choice says anything about you.

Get a grading report from a recognized lab, whatever you buy. Don't buy a loose stone without one.

The money, plainly

The "three months' salary" rule was an advertising campaign. It came from a jeweller's marketing department, not from anywhere sensible. Treat it as such.

Set a number you can pay in full, in cash, without moving anything around. If the ring requires a financing plan, it's the wrong ring, and she'd almost certainly agree with that if you asked her.

Once you've bought it, get a written appraisal and call your insurance agent about adding it to your policy. A ring sitting uninsured in a nightstand is one distracted afternoon from being gone. Your agent will tell you what they need.

Her father

Ask him. Not because she's property, and not because his answer is binding. Because it's a way of telling the people who raised her that you intend to be serious, and because the man who does this on a Tuesday afternoon has done something he'll be glad of in fifteen years.

Say it straight. You love his daughter, you want to marry her, you'd like his blessing. Have a real answer ready for how you'll provide and where you'll live, because he may ask, and he's entitled to.

If her family is fractured, or there's no father to ask, ask whoever stood in that place. If he says no and you're certain, you proceed anyway, and you keep the door open for the rest of your life.

Then just ask her

Skip the drone crew. Skip the flash mob. The good ones are almost always private, in a place that means something to the two of you, followed by dinner with people who love you both.

One friend with a phone is enough photography.

Have words prepared and say them out loud. Not a speech. Three or four sentences about who she's and what you're committing to. Say them before you produce the box, because once the box is out she stops listening.

You'll have forgotten the clarity grade inside two years. She'll be able to repeat what you said for the rest of her life.