Finding the perfect ring sized opal

Whether it’s for you or a gift for someone special, choosing the right opal can be challenging. One consideration is always the size of the opal. Is it going to be the right size for the design I want?

This video is for anyone who has no idea how to translate millimetres into actual visuals. All opals featured are for sale (as at blog publication date).

So how big should an opal be for a ring? This is like asking – how long is a piece of string?! It depends on the type of ring and also the size of the fingers it is going on.

In this video I use my hands which are on the small size. My finger size is K or 5 1/2 for those watching in the US.

Unlike diamonds where you can specify a size and that will roughly correspond to a carat weight, opals come in all thicknesses so a 3ct stone can have the same face size as a seven carat stone.


Lets start with a one carat stone. These two above are 1ct and 1.05cts. The green red stone is 7.5×6.5 and the crystal is 7 x6mm. You can see that both look dainty on my fingers and would make excellent simple dress rings or even engagement style rings with the addition of other colored gems or diamonds as shoulders or as a halo surrounding the opal. Whatever design you choose these stones whilst small are still certain to make an impact.


These next two above are larger and can easily stand on their own. The black opal  on my middle finger weighs 3.25cts and measures 11x9x5mm. set horizontally or vertically , high up or low down to the finger, it demands to be seen. No one will miss an opal this size.

The crystal on my ring finger is over a carat smaller at 2.11ct and measures 10x7mm. I’ve orientated this sideways as this particular stone is double sided. I’d love to see it set in a swivel ring – a design that was popular with the Etruscans and Greeks (and the Egyptians before them). I think set this way it would be pretty substantial on any finger.


The opals above are what, for me I would consider getting into cocktail size. These differ greatly in cart weight. The crystal is 2.86cts and measures 12x10x3.5mm. The semi black is a whopping 7.88cts and is only slightly bigger on the face at 13×12. The difference in carat weight is obvious through in the thickness of the stone with the semi black being 8mm. This stone would make one magnificenct knuckle duster – whether you have small fingers like me or larger and much longer fingers. These sizes are also suitable for pendants.


9.72ct semi black opal 21x13x5mm
9.72ct semi black opal 21x13x5mm

The final stone is one of my favourites in our collection. Up close it has a 3 dimensional effect that makes it shimmer and dance like all the very best opals. It exudes great energy and life. At 9.72cts it’s probably too big for me but I really love it so I would wear it regardless.

So there you have it, a  sample of our collection with my hands as a guide. I hope it helps next time you are looking for the perfect ring sized opal.



2 thoughts on “Finding the perfect ring sized opal”

  1. Hi Ruth. Thanks for showing us how the different size opals look on a hand. This will help with working out which will be best suited to multi-stone rings, solitaires (from delicate to eye popping cocktail) and even pendants. I’ve drawn little cardboard cutouts in the past but there is nothing like seeing it. It was also very helpful to see the how the opals with different depths look on a finger : )
    All the best. Jocelyn

    • Hi Jocelyn I am very happy to have helped you out. Yes opal can be hard to judge on a flat computer screen. Thanks for the comments


Leave a Comment

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.

The reCAPTCHA verification period has expired. Please reload the page.

Item added to cart.
0 items - $0.00