What US ring size is 16.51 mm inner diameter?

On the NOOI chart, 16.51 mm inner diameter is US 6 (UK L½, Italian 11.9).

What US ring size is 54.4 mm inner circumference?

On the NOOI chart, 54.4 mm inner circumference is US 7. EU / ISO ring size is this circumference in millimetres.

What US size is UK L½?

UK L½ is US 6 on the NOOI chart.

What US size is Italian 13.8?

Italian 13.8 is US 6¾ on the NOOI chart (same row as 17.12 mm inner diameter).

Is Italian ring size the same as Japanese?

No. On the NOOI chart, US 6 is Italian 11.9 and Japanese 11. The Japanese column is East Asia (China, South Korea), not the Italian scale.

1 9

Princess Cut Lab Grown Diamond Ring, Floral, Certified, 18k

€2.194,00

Sale Sold out

Taxes included. Shipping calculated at checkout.

Crafted from solid 18k gold

Handcrafted and made to order.
Free DHL Express shipping, fully insured & trackable.
Secure packaging with signature delivery.

Duties & taxes may apply for international orders.

DESCRIPTION

A floral engagement ring in 18k gold, made by hand in Italy. The centre is a lab-grown diamond, princess cut, 5×5 mm, 0.8 ct, color D–F, clarity VS, certified (IGI or similar). Ten round natural diamonds sit beside it: two of 1.5 mm, two of 1.25 mm, and six of 1 mm, color G, clarity VS.

The same floral ring with a moissanite centre: princess cut moissanite floral ring.

Details:
Main Stone: Lab-grown diamond, 5×5 mm princess cut, 0.8 ct, color D–F, clarity VS, certified (IGI or similar)

Side Stones: 2 round natural diamonds, 1.5 mm, 2 round natural diamonds, 1.25 mm, and 6 round natural diamonds, 1 mm, color G, clarity VS

Metal: 18K Solid Gold (Yellow, Natural White gold, white+rhodium or Rose Gold)

Design: Floral clusters on a beaded band. Band 1.4 mm at the top, 1.9 mm at the bottom

Made to order.

Natural white gold
Please choose your favourite gold colour from the drop-down menu.
We don’t rhodium-plate our white gold. Instead, it keeps its original champagne shade — a slight hint of yellow or grey, not bright white. That is the look we prefer: it doesn’t need re-plating later.
If you want a cooler, classic white, select white + rhodium.

R 340 Lab Grown

Thanks!
NOOI
www.nooijewelry.com

ASK A QUESTION ABOUT THIS ITEM

SHIPPING INFORMATION

All of our jewelry is only available to order and made 100% by hand in Italy, which is why delivery may take 20 to 25 business days.

For more detailed information about your purchase, please feel free to email us nooijewelry@gmail.com

PAYMENT INFO

We accept all major payment methods:
Credit cards (Visa, MasterCard, American Express, Maestro, UnionPay), Klarna, Paypal, Apple Pay, Google Pay, Amazon Pay and bank transfer.

FAQ

How does Nooi Jewelry ensure the quality of its products?

At Nooi Jewelry, we are committed to delivering the highest quality products to our customers. Each piece of jewelry undergoes rigorous quality checks at every stage of production, from material selection to final inspection. We ensure that every item meets our strict standards for craftsmanship and durability. For more details, please visit our Quality Assurance page.

View full details

How to measure your ring size

At NOOI we make every ring in a US size, converted from inner diameter — the most accurate way to convert a ring size. A digital caliper on a ring that already fits is the method we trust.

If you know your ring size, but it isn’t listed in US sizing—and you’re not familiar with how ring sizes convert—feel free to contact us.

Ring size converter

From internal diameterbetter if you measure with a digital caliper

From UK letter

From inner circumference

From Italian sizealso Spain, Netherlands, Switzerland

From Japanese sizeChina, South Korea — not the Italian scale

Use one field, then convert. The tool picks the nearest US size on the chart, including quarter sizes (¼, ½, ¾).

Ring size chart

Inner diameter and circumference in millimetres. Shop size = United States (also Canada and Mexico). Convert highlights the row and circles the US size.

Ø mm	Circ. mm	US	UK	East Asia	India	IT / ES / NL / CH
11.63	36.5	0	—	—	—	—
11.84	37.2	¼	—	—	—	—
12.04	37.8	½	A	—	—	—
12.24	38.5	¾	A½	—	—	—
12.45	39.1	1	B	1	—	—
12.65	39.7	1¼	B½	—	—	—
12.85	40.4	1½	C	—	—	0.4
13.06	41.0	1¾	C½	—	—	—
13.26	41.7	2	D	—	—	—
13.46	42.3	2¼	D½	—	—	—
13.67	42.9	2½	E	—	—	—
13.87	43.6	2¾	E½	—	—	—
14.07	44.2	3	F	4	—	4.2
14.27	44.8	3¼	F½	5	5	4.8
14.48	45.5	3½	G	—	—	5.5
14.68	46.1	3¾	G½	6	6	6.1
14.88	46.8	4	H	7	—	6.8
15.09	47.4	4¼	H½	—	7	7.4
15.29	48.0	4½	I	8	8	8
15.49	48.7	4¾	J	—	9	8.7
15.70	49.3	5	J½	9	—	9.3
15.90	50.0	5¼	K	—	10	10
16.10	50.6	5½	K½	10	—	10.6
16.31	51.2	5¾	L	—	11	11.2
16.51	51.9	6	L½	11	12	11.9
16.71	52.5	6¼	M	12	—	12.5
16.92	53.1	6½	M½	13	13	13.1
17.12	53.8	6¾	N	—	—	13.8
17.32	54.4	7	N½	14	14	14.4
17.53	55.1	7¼	O	—	15	15.1
17.73	55.7	7½	O½	15	—	15.7
17.93	56.3	7¾	P	—	16	16.3
18.14	57.0	8	P½	16	17	17
18.34	57.6	8¼	P¾	—	—	17.6
18.54	58.3	8½	Q¼	17	18	18.3
18.75	58.9	8¾	R	—	19	18.9
18.95	59.5	9	R½	18	—	19.5
19.15	60.2	9¼	S	—	20	20.2
19.35	60.8	9½	S½	19	21	20.8
19.56	61.4	9¾	T	—	—	21.4
19.76	62.1	10	T½	20	22	22.1
19.96	62.7	10¼	U	21	23	22.7
20.17	63.4	10½	U½	22	—	23.4
20.37	64.0	10¾	V	—	24	24
20.57	64.6	11	V½	23	25	24.6
20.78	65.3	11¼	W	—	—	25.3
20.98	65.9	11½	W½	24	26	25.9
21.18	66.6	11¾	X	—	—	26.6
21.39	67.2	12	X½	25	27	27.2
21.59	67.8	12¼	Y	—	28	27.8
21.79	68.5	12½	Y½	26	—	28.5
22.00	69.1	12¾	Z	—	29	29.1
22.20	69.7	13	Z½	27	30	29.7
22.40	70.4	13¼	Z1	—	—	30.4
22.61	71.0	13½	—	—	31	31
22.81	71.7	13¾	Z2	—	32	31.7
23.01	72.3	14	Z3	—	—	32.3
23.22	72.9	14¼	—	—	33	32.9
23.42	73.6	14½	Z4	—	—	33.6
23.62	74.2	14¾	—	—	34	34.2
23.83	74.8	15	—	—	35	34.8
24.03	75.5	15¼	—	—	—	35.5
24.23	76.1	15½	—	—	36	36.1
24.43	76.8	15¾	—	—	—	36.8
24.64	77.4	16	—	—	37	37.4

After you order

At checkout, pick the closest US size. If you are not entirely certain, feel free to email us the inner diameter in millimetres. We will make the ring to that diameter.

How to measure the inner diameter

Take a ring that already sits well on the intended finger.
Measure the inside diameter with a digital caliper, in millimetres, straight across the centre (to be more accurate, measure in a few spots).
Choose the matching US size so you can check out, then email us that same millimetre figure after the order.

Do not wrap string or paper around the finger. That gives a circumference, not the inner diameter we make to.

Convert inner diameter to US ring size

Measure the inside of a ring that fits, in millimetres, then convert. On the NOOI chart: 16.51 mm = US 6, 17.32 mm = US 7, 18.14 mm = US 8.

Convert inner circumference to US ring size

Inner circumference in millimetres is the EU / ISO size. On the NOOI chart: 51.9 mm = US 6, 54.4 mm = US 7, 57.0 mm = US 8.

Convert UK letter to US ring size

On the NOOI chart: L½ = US 6, N½ = US 7, P½ = US 8.

Convert Italian size to US ring size

Italian size is also used in Spain, the Netherlands and Switzerland — not Japan. On the NOOI chart: 11.9 = US 6, 13.8 = US 6¾, 14.4 = US 7.

Common conversions (NOOI chart)

You have	US size
16.51 mm inner diameter	6
17.32 mm inner diameter	7
18.14 mm inner diameter	8
51.9 mm inner circumference	6
54.4 mm inner circumference	7
57.0 mm inner circumference	8
UK L½	6
UK N½	7
Italian 11.9	6
Italian 13.8	6¾
Japanese 11	6

Ring size questions

What US ring size is 16.51 mm inner diameter?: US 6 on the NOOI chart (UK L½, Italian 11.9).
What US ring size is 54.4 mm inner circumference?: US 7. EU / ISO size is this circumference in millimetres.
What US size is UK L½?: US 6.
What US size is Italian 13.8?: US 6¾ (17.12 mm inner diameter).
Is Italian ring size the same as Japanese?: No. US 6 is Italian 11.9 and Japanese 11. The Japanese column is East Asia, not the Italian scale.