The proposal checklist: ring, size, timing and peace of mind

Work backwards from the date you want to propose, and build in a margin. A custom diamond ring takes about four to six weeks, so a ring ordered at the edge of that range leaves no room for a correction.

The table below is a sensible plan rather than a rule. Shorten it if you are buying a ready-made ring, and lengthen it if the proposal is tied to a trip, a holiday or a family gathering that cannot move.

GIA suggests borrowing a ring your partner already wears on the ring finger, ideally a plain band, and taking it to a jeweller to be measured on a mandrel. You can also press the ring into a bar of soap and bring the imprint, or trace the inside of the band on paper. A friend or relative may know the size.

Fingers change size. GIA also observes that a finger measures smaller in cold weather and larger in heat, and that humidity, altitude and the time of day can shift it too. A wide band usually needs a slightly larger size because it fits more snugly, and a large knuckle makes a ring harder to slide on. Measure on more than one day if you can.

If you are unsure, aim a little large. A jeweller can take metal out of an oversized ring more easily than add metal to one that is too tight. Rings with pavé and channel settings cannot be resized easily, and full eternity bands can be very difficult to resize, so getting the size right matters more for those. The ring size guide and the ring size entry go through each method step by step.

A jeweller will ask for the same few things, so decide them first. GIA's list of questions a jeweller will ask includes your proposal date, your budget, the diamond shape, the ring style, the metal colour and the ring size. If you know a little about the 4Cs, the conversation is shorter.

• Budget. Pick a number you can pay without strain. The engagement ring budget guide explains what drives cost, and the three months' salary rule article traces where that old guideline came from.
• Shape and setting. The diamond shapes guide and settings guide compare the choices.
• Metal and stone type. A custom engagement ring can use a natural diamond, a lab-grown diamond or moissanite. The lab-grown vs natural guide compares them.
• Custom or ready-made. If you want something designed around your partner, begin in the design studio and allow the longer timeline.

If you are choosing from scratch, the guide to choosing an engagement ring works through the same decisions in order.

Keep three things together and photograph each of them.

1. The receipt. It should describe the ring in enough detail to identify it. Ask in writing how resizing, repairs and returns are handled before you pay.
2. The grading report, if the centre stone has one. GIA advises insisting on a diamond grading report from an independent lab, which tells you the identity and quality of the stone and maps its clarity characteristics. If the stone has a laser inscription, the number can be matched to the report, and it can be entered into GIA Report Check. The guide to reading a report explains each field.
3. An appraisal, if your insurer asks for one. GIA defines an appraisal as an evaluation of diamonds or jewellery, usually for insurance or estate purposes, and notes that insurers often require one to set the replacement value. A jewellery appraisal is a different document from a grading report.

Store the originals somewhere separate from the ring, and keep a digital copy as well.

Treat insurance as a question to ask, not a box to tick. GIA, writing for a US audience, says most homeowner's and renter's policies offer relatively inexpensive cover for jewellery theft, and advises making sure the policy also covers damage and loss. Canadian policies vary, so put these questions to your own insurer or broker:

• Is the ring covered, and up to what amount, under your current policy?
• Do you need a separate schedule or endorsement for it?
• Does the insurer want an appraisal or the grading report?
• Does cover include accidental damage and loss, as well as theft?
• Does it apply when the ring is away from home, such as on a trip?
• From what date does it start: purchase, pickup or the proposal?

Ask for the answers in writing. Do not assume, since the answer decides what you will be paid if the ring is lost.

Choose a hiding place that is also secure: not a coat pocket or a drawer that someone else uses. GIA's advice is to keep each piece of diamond jewellery in its own padded box or soft pouch rather than sharing one container.

If you are travelling to propose, carry the ring yourself rather than packing it in a checked bag, and keep the receipt and report with you or in a photo on your phone. Ask your insurer whether cover applies away from home. Check the prongs and mounting at pickup: A loose diamond can wear through a prong over time, so have the prongs checked every six months.

Avoid wearing or handling the ring before the day. A ring that is tried on, cleaned or carried loose is more likely to be knocked or dropped.

A few things usually follow. If the size is slightly off, bring the ring and receipt back to the jeweller for resizing, and ask how long it will take. If you want a message inside the band, ask about engraving. Update your insurer with the appraisal or report once you hold them.

The wedding band is the next purchase. The guide to choosing a wedding band explains how to match metal, width and profile to the engagement ring, and the stacking rings article shows how they sit together. You can see rings in person at one of the showrooms, or book a video appointment.