How to Choose an Eternity Ring: Full vs Half, and Getting the Size Right

An eternity ring is a ring of equally sized diamonds set in an unbroken line. The name comes from reading eternity into that unbroken light.

The questions that come up are almost always the same. Full or half. Which carat. How to decide the size. Whether it can be a gift. This guide was written so that each of them leaves with an answer.

From our designer Haruna Mori's own layering in Paris. Swipe across; the links under each photo open the product pages.

• Full or half: the only difference is where the diamonds sit
• How they differ in daily life
• The charm of a full eternity, and how to choose one
• The charm of a half eternity
• The joy of layering, shared by both
• How to choose
• Choosing from your budget
• ANNA DIAMOND eternity rings, all fourteen
• Deciding your size
• Living with it every day
• Frequently asked questions

When this ring comes into your life

In Europe and the United States, it is traditionally a ring for a tenth wedding anniversary or the birth of a child. In Japan, more and more people layer it with their engagement and wedding rings, or welcome one at a milestone of their own.

It can be a day with a reason, or a day without one. We believe the day you decide to welcome it becomes the anniversary.

Full or half: the only difference is where the diamonds sit

A full eternity ring is circled by diamonds all the way around the finger. A half eternity carries diamonds only on the upper half, leaving the palm side in metal.

One important thing before anything else. Seen from the front, the two look almost identical. The palm side is hardly ever seen. The difference shows itself not in the look, but in small moments of daily life.

How they differ in daily life

A ring turns, little by little, through the day. A full eternity always has diamonds facing up, however far it turns. With a half eternity, the metal side sometimes comes around, and a small gesture is born: nudging it back with a fingertip.

Finger sizes change over the years. A half eternity has a stoneless section, so it can be resized, by one or two Japanese sizes as a guide. A full eternity has stones all the way around and cannot be resized, so the first sizing is done with extra care.

Hands bump into more things than you think. Desks, door handles, washbasins. A half eternity keeps metal on the palm side, so there is little worry about the stones and it wears easily every day. A full eternity carries stones there too, and asks for a small lifelong courtesy: not knocking it hard.

Price follows the number of stones. A half eternity carries roughly half the stones of a full, so the view from the front stays almost the same while the price comes down.

The charm of a full eternity, and how to choose one

The charm of a full eternity is that at every moment, from every angle, there are diamonds in view. Whatever your hands are doing, there is light where your eyes happen to fall. And the person made happiest by that is not anyone around you. It is you.

On the outer fingers, the index or the pinkie, more of the ring's circumference stays visible. That is where a full eternity comes into its own. It is why we make a 1.1ct full eternity for the pinkie.

Its weakness is that it cannot be resized. So when choosing a full eternity, we recommend a size that fits about two of your fingers. On a day your fingers swell, it moves to another finger. Keeping that choice open makes up for the resizing it cannot have.

The charm of a half eternity

The charm of a half eternity is that it can be worn every day without a second thought. With metal on the palm side, housework and desk work go on as usual.

With roughly half the stones of a full, the same budget reaches a larger diamond. Being resizable is another comfort over the long run.

And once you begin layering half eternities of different sizes, your hand suddenly has a wardrobe.

The joy of layering, shared by both

There is one great charm the two share: the way an eternity ring widens everything else you wear.

An eternity ring is the simplest ring there is, one shape repeated. So it never argues with another ring. Layered with a sculptural ring, it lifts that ring's character. Stacking eternities of different sizes or metals is lovely too.

Our designer layers a platinum half eternity over silver jewellery, or wears a 1ct beside a 0.3ct. When the stone sizes and metals differ just slightly, the styling of the hand gains depth.

The secret to layering beautifully is a single shared element. Match the metal colour, the stone size, or the slimness of the band. With one thing in common, the whole settles together.

How to choose

• If you want it shining however it turns: choose a full eternity. The diamonds never break off, at any moment. Pick a size that fits about two of your fingers.
• For long, easy, everyday wear: a half eternity suits you. It can be resized, and the palm side asks nothing of you. It is why halves have long been chosen as wedding bands.
• For the largest brilliance within a budget: a half eternity gives you the same front view at roughly half the stones.

Whichever you choose, the light seen from the front is the same. What differs is how you live with the ring.

Choosing from your budget

Here is a guide at ANNA DIAMOND's actual prices. Every ring uses lab-grown diamonds of F colour or above and VS clarity or above. Prices appear in your local currency in our store; shipping is free worldwide and import duties are covered by us.

Budget	What it reaches	Price
Up to ¥100,000	Half eternity 0.3ct	from ¥88,000
¥100,000 range	Full eternity 0.7ct (10K) / Full eternity 1.1ct for the pinkie	¥121,000 / ¥176,000
From around ¥200,000	1ct eternity rings	from ¥198,000

One note about carats. The 1ct of an eternity ring is the total of every stone in the row. At the same 1ct, more stones mean each one is smaller and finer; fewer stones mean each is larger, with a clearer outline.

ANNA DIAMOND eternity rings

All fourteen eternity rings currently available. Swipe across to browse.

Prices include Japanese tax and appear in your local currency in our store. Tap a card to open the product page.

Deciding your size

Finger sizes change with the season and the hour: slimmer in the morning, fuller by evening. We recommend measuring in the afternoon, when hands are neither cold nor swollen.

We lend ring gauges free of charge, so do use one before deciding. You are also welcome to ask us anything through the contact page, photos and videos included.

Because a full eternity cannot be resized, this check matters most there. And if it loosens over the years, a slim ring stacked above it will hold it in place.

Living with it every day

Washing your hands and doing the dishes are fine with the ring on. Neither platinum, gold nor a lab-grown diamond is harmed by water.

At hot springs and pools, it is safer to take it off. Sulphur and chlorine can dull the metal's surface.

When you sleep, we recommend taking it off. No stray force reaches the ring, and putting it back on in the morning becomes a small beginning to the day.

For everyday care, a gentle wipe with a soft cloth is enough. If oils build up, wash it gently in lukewarm water with a mild detergent. Cleaning is free for life at our gallery in Tokyo.

About the metals

Frequently asked questions

Can it be an engagement ring or a wedding band?

There is no rule. Some choose an eternity ring as an engagement ring; others wear one daily as a wedding band. For everyday wear, the resizable half eternity is the more common choice.

Which finger should it go on?

There is no rule. We believe the finger you want to wear it on is the right one. We also design for specific fingers, like the 1.1ct made for the pinkie.

I want to give one as a gift, but I do not know the size.

If you can borrow one of their rings, we can work out the size at our gallery or through the contact page. If that is difficult, a half eternity, which can be resized afterwards, is the safe choice.

What happens if a stone comes out?

Every ring carries a 2-year quality warranty, and we continue to take repairs after it ends. Please get in touch first.

I need it quickly.

Pieces in stock are dispatched within 2 to 5 days of your order. See our ready-to-ship jewellery.

After your purchase

ANNA DIAMOND offers 7-day returns, a 2-year quality warranty and complimentary lifetime cleaning at our gallery in Tokyo. A half eternity can be resized once, free of charge, within a year of purchase. Shipping is free worldwide and import duties are covered by us.

See them in person

How a ring turns, and how the palm side feels: these are things you only learn by wearing one. At the ANNA DIAMOND Gallery in Daikanyama, Tokyo, you can try on and purchase with no reservation needed.

Browse all of our rings here. To learn about the stones themselves, see our page on lab-grown diamonds; if you are thinking of one as an engagement ring, our engagement ring guide is the place to start.

The full-circle option is explored further in our guide to full eternity rings.