Size Guide
Choosing the perfect ring size is an essential part of the Hardy Brothers experience.
Our guide below will help you find the most accurate fit, ensuring comfort, elegance, and a seamless expression of luxury.
| Australian Size | Inside Circumference (mm) |
|---|---|
| H | 46.0 |
| H ½ | 46.6 |
| I | 47.2 |
| I ½ | 47.9 |
| J | 48.3 |
| J ½ | 49.3 |
| K | 49.6 |
| K ½ | 50.3 |
| L | 50.5 |
| L ½ | 51.5 |
| M | 51.8 |
| M ½ | 52.5 |
| N | 53.1 |
| N ½ | 53.8 |
| O | 54.5 |
| O ½ | 54.8 |
| P | 55.7 |
| P ½ | 56.4 |
| Q | 57.1 |
| Q ½ | 57.6 |
| R | 58.4 |
| R ½ | 59.1 |
For the most precise fit, we invite you to visit a Hardy Brothers boutique where our specialists will personally measure your finger and ensure your chosen piece is crafted to perfection.

Hardy Brothers uses standard Australian ring sizes.
| Australian Size | Inside Circumference(mm) |
| M 1/2 | 55.7 |
| N | 57.0 |
| N 1/2 | 58.3 |
| O | 59.6 |
| O 1/2 | 60.9 |
| P | 62.2 |
| P 1/2 | 63.5 |

Cut out the length chart
Measure your wrist
Subtract the case size of the timepiece from your wrist measurement
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Measure this box to check accuracy


Enquire about Jacob & Co. Astronomia Solar Planets Zodiac 43.40MM
Details
| Vendor | Jacob & Co |
| Metal | 18ct Rose Gold |
Read more information regarding our Product Disclaimers.
Product Details
The Astronomia is the epitome of 21st century haute horlogerie and a globally recognized symbol of Jacob & Co. watchmaking expertise. A world-first both in the boldness of its unprecedented concept and its entirely mechanical construction, the Astronomia has gone beyond impressive horological achievements and has been regarded as an outstanding multidisciplinary engineering achievement. Re-engineered from the ground up, the Astronomia Solar is the most compact in our peerless collection of Astronomia calibers.
Despite its close-packed design, the Astronomia Solar Planets Jewelry displays the precious planets of our Solar System as Jacob-Cut®, 288-facet gemstone spheres, placed on the rotating platform of the Astronomia Solar caliber. Its three main arms carry the differential-driven, self-leveling time display, the magnesium globe in hand-painted blue for a spectacular representation of Planet Earth, the one-minute flying tourbillon regulating organ. Its subsidiary arms carry three Jacob-Cut®, 288-facet stones, along with a center-mounted, 1.5ct Citrine stone to represent our Sun. The Astronomia Solar Planets Jewelry makes for a beautifully artistic, highly refined and fully mechanical recreation of our solar system, to be appreciated like it has never been done before.

























