An engagement ring is often treated as if it comes with instructions.

A diamond. A proposal. A certain shape. A certain finger. A certain idea of what the ring is meant to be.

The assumptions are often so ingrained that it's easy to forget that they're assumptions at all.

An engagement ring is an object that exists at a certain point in the life of two people. It might signify a promise, a beginning, an end, or even just the decision to build a life together. The assumptions around it can be helpful. They should not overshadow the people the ring ultimately belongs to.

The right ring is not the one that most convincingly plays its role.

It is the one that makes the most sense to the woman who will wear it.

Start with the person, not the parameters

The engagement-ring market is one that prides itself on comparison.

Carat weight. Diamond shape. Setting. Metal. Price. Certification. The list goes on.

These are all valid considerations.

They are not the starting point.

The simplest question is the most obvious one:

What does she actually wear?

Look at the jewelry she already owns.

Does she wear yellow or white gold?

Are her rings simple or substantial?

Does she wear jewelry every day, or only on special occasions?

Does she favor pieces that disappear under a sleeve, or ones that demand attention?

An engagement ring should not feel like something that comes from another world.

It should feel like something that makes sense for the woman who will wear it.

The ring does not have to be a surprise

There is a popular idea that choosing an engagement ring together somehow detracts from the romance of the moment.

It does not.

A ring is an object that is worn every day, and the details of its construction matter.

Choosing one together can be an exercise in intimacy, if both people are willing to put in the work.

Some couples know what they want before they start looking. Some discover their preferences as they go. Some agree on the diamond but not the setting, or the setting but not the diamond. Some people choose the ring after the proposal has already been made.

There is no right way to make this choice.

The best arrangement is the one that makes both people comfortable.

The diamond is not the whole ring

Diamond size is an easy conversation when it comes to engagement rings.

It is also one of the least useful ones.

A diamond's carat weight tells you how much it weighs. It says little about how beautiful it is, how well it is cut, how it interacts with the light, how it fits in a given setting, or how it looks on a woman's hand.

A smaller diamond with excellent proportions can look far more impressive than a larger one that has been cut for visual weight alone.

The same goes for the rest of the ring.

The height of the setting can change the way the diamond sits on the hand.

The width of the band can change the way the ring feels on the finger.

The relationship between the two can change the way the whole object looks.

The ring should be considered as a whole.

Not as a diamond that has been bought separately and mounted on a band afterwards.

Shape is personal

Round, oval, cushion, emerald, pear, marquise, radiant.

The list goes on.

The decision does not have to.

Different diamond shapes have different proportions, and different proportions create different visual effects.

Some make the finger look longer.

Some have a more squared appearance.

Some shapes are far more geometric than others.

There is no single best diamond shape.

The right one is the one that looks best on the woman's hand, and that she will still like after the initial shock of the proposal has worn off.

That last part is especially important.

An engagement ring is often photographed dozens, if not hundreds of times in the weeks after it is given.

It is also worn for the rest of the woman's life.

The decision should be made with the long term in mind.

The setting changes the ring

A diamond does not exist in isolation, and the way it is set in a ring can change the way it looks and feels.

A solitaire setting leaves the center diamond to speak for itself.

A halo setting surrounds it with other diamonds, adding weight and visual impact.

A bezel setting follows the shape of the diamond, creating a more enclosed, architectural look.

Three-stone settings create a sense of proportion and balance by using two smaller diamonds to frame a larger one.

Pavé settings change the texture of the band, making it look heavier and more detailed.

These are all valid options.

They are not simply decorative touches.

They change the feel and construction of the whole ring.

The setting should be chosen alongside the diamond, rather than as an afterthought.

Metal is part of the decision

The metal of the ring is important in two ways: the way it looks, and the way it feels.

Yellow gold has warmth.

White gold has presence.

Rose gold has color.

Platinum has weight.

There is no rule that says an engagement ring has to be made of white gold, or that it cannot be made of yellow gold.

The woman's jewelry collection is often a more useful guide than any rule of thumb.

If she wears mostly yellow gold, a white gold engagement ring might feel strangely out of place, despite popular assumptions.

The occasion does not dictate the metal.

Consider the life after the proposal

An engagement ring is one of the few luxury items that is purchased with the expectation that it will be worn for a long time.

It will see the woman through her career.

It will see her through vacations and holidays, through children and life changes.

It makes sense to consider its practical implications before buying it.

Ask about the construction of the ring, and the security of the diamond.

Ask if it can be resized, or repaired, if necessary.

Ask if it can accommodate a wedding band, if that is an option.

These are not unromantic questions.

They are simply practical ones, that ask whether this object is right for the life it needs to accompany.

The wedding band does not have to match

There is no rule that says a wedding band has to look as if it was designed to go with the engagement ring.

Sometimes it should.

Sometimes it should not.

A simple band can create a nice contrast with a more elaborate engagement ring.

A band with texture or detail can complement it.

A band made of a different material can create a nice juxtaposition with a gold engagement ring.

The most important consideration is the way the two rings look together on the woman's hand.

Matching is an option.

It is not a requirement.

What should an engagement ring cost?

There is no single right answer.

The old rules about how many carats the ring should weigh, or how much it should cost in relation to one's salary, have no bearing on reality.

The right budget is the one that makes sense for the woman and her finances.

The ring should not be something that causes financial strain simply because it is an engagement ring.

Nor should it feel like a humiliation to spend more money on it than one is comfortable spending.

The useful rule of thumb is to compare the value of the ring to the value of what it is: a diamond, a metal, a particular design, and a certain amount of craftsmanship.

Price is information.

It is not meaning.

A ring can be chosen outside of the script

The standard engagement-ring story is a small one: one person buys a ring, the other person is surprised by it, the ring is given during a proposal, the wedding takes place, and the ring is worn afterwards.

The details of real life are often far more complicated.

Some women choose their own rings.

Some people choose them together.

Some people propose without one at all.

Some rings are inherited.

Some are altered.

Some marriages happen later in life, and deserve something different from a young couple just getting engaged.

The object can change, and the meaning of it need not be diminished by those changes.

What makes a ring right?

Not the biggest diamond.

Not the most expensive price tag.

Not the most popular setting.

Not the most impressive display piece in a jewelry store.

The right ring is the one that fits the woman who will wear it.

It looks good on her hand.

It feels right for her style.

It can keep up with the life she leads.

And, ideally, it will become less and less about the proposal as time goes by.

That is the strange thing about a good engagement ring.

It marks a moment in time, but it also lasts long after that moment has passed.

It becomes part of everyday life.

The morning coffee.

The day job.

Vacations.

Hard times.

Good times.

The photograph of the wedding may still be tucked away somewhere in an album.

The ring still remains on her hand.

The moment begins the story, but it is not the whole thing.