Nitida Jewellery Size (Australia / UK)	Inside Diameter (mm)	USA / Canada Size
D	13.1
D 1/2	13.3	2
E	13.5
E 1/2	13.7	2.5
F	13.9
F 1/2	14.1	3
G	14.3
G 1/2	14.5	3 1/2
H	14.7
H 1/2	14.9	4
I	15.1
I 1/2	15.3	4 1/2
J	15.5
J 1/2	15.7	5
K	15.9
K 1/2	16.1	5 1/2
L	16.3
L 1/2	16.5	6
M	16.7
M 1/2	16.9	6 1/2
N	17.1
N 1/2	17.3	7
O	17.5
O 1/2	17.7	7 1/2
P	17.9
P 1/2	18.1	8
Q	18.3
Q 1/2	18.5	8 1/2
R	18.8
R 1/2	19	9
S	19.2
S 1/2	19.4	9 1/2
T	19.6
T 1/2	19.8	10
U	20
U 1/2	20.2	1O 1/2
V	20.4
V 1/2	20.6	11
W	20.8
W 1/2	21	11 1/2
X	21.2
X 1/2	21.4	12
Y	21.6
Y 1/2	21.8	12 1/2
Z	22
Z 1/2	22.2	13
Z+1	22.4
Z+1 1/2	22.6	13 1/2
Z+2	22.8
Z+2 1/2	23.95	14
Z+3	23.15