Constellation Birthstone Ring — December
Constellation Birthstone Ring — December
Regular price
$95.00
Regular price
Sale price
$95.00
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per
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Our Constellation Birthstone Ring in December is a deeply personal piece made to be worn every day. Icy blue topaz stones scatter across a delicate band like stars across the night sky — cool, crisp and quietly breathtaking.
Available in gold.
- Round cubic zirconias in a scattered constellation setting.
- 925 sterling silver, 18k gold plated.
Size Guide
Ring size guide
All Zostma rings are listed in US sizes. Use the table below to find your size, or use the country dropdown to compare with your local sizing.
| Zostma (US) size | Diameter / Circumference (mm) | Australia / UK / Ireland |
|---|
How to measure
1
Cut a strip of paper or piece of stringAbout 10cm long and no wider than 1cm.
2
Wrap it around your fingerWrap snugly around the base of the finger you want to wear the ring on. Make sure it can slide over your knuckle.
3
Mark the overlap pointUse a pen to mark where the paper or string meets itself.
4
Measure the lengthLay it flat and measure the length in mm — this is your circumference. Divide by 3.14 to get your diameter.
5
Match to the table aboveFind your circumference or diameter in the table to get your Zostma size.
Measure at the end of the day when fingers are at their largest. Fingers can change size depending on temperature and time of day.
1
Find a ring that fits wellPick a ring that fits the finger you want to wear your new ring on.
2
Measure the inside diameterUse a ruler to measure the inside diameter of the ring in mm — measure straight across the inside of the ring at its widest point.
3
Match to the table aboveFind your diameter in the table to get your Zostma size.
If you are between two sizes, we recommend sizing up for comfort.
Stacking rings? If you plan to stack multiple rings on the same finger, consider sizing up by half a size to allow room for layering comfortably.
Bracelet size guide
Zostma bracelets are available in set lengths in cm. Use the table below and measuring guide to find your best fit.
| Zostma size | Wrist circumference (cm) | Fit |
|---|---|---|
| 17 cm | 14 – 15 cm | Snug / close fit |
| 18 cm | 15 – 16 cm | Classic fit |
| 19 cm | 16 – 17 cm | Relaxed fit |
| 20 cm | 17 – 18 cm | Loose / layering fit |
How to measure your wrist
1
Cut a strip of paper or use a piece of stringAbout 25cm long.
2
Wrap around your wristWrap just below your wrist bone — where you would naturally wear a bracelet.
3
Mark the overlapMark where the paper or string meets itself.
4
Measure the length in cmThis is your wrist circumference. Add 2–3 cm for a comfortable fit, or 3–4 cm if you prefer a looser, layered look.
5
Match to the table aboveFind the size that matches your wrist plus your preferred extra room.
For a snug tennis bracelet fit, add 2 cm. For a relaxed chain bracelet or layered stack, add 3–4 cm.
Layering bracelets? When stacking multiple bracelets, go up one size (e.g. from 17 cm to 18 cm) so the pieces sit comfortably without feeling tight. Mixing a snug tennis bracelet with a looser chain creates a beautifully curated stack.
Necklace & pendant size guide
Use the table below to understand where each chain length will sit on your body, then use the string method to visualise before you buy.
| Length (cm) | Length (inches) | Where it sits |
|---|---|---|
| 35 – 40 cm | 14 – 16" | Choker — sits at the collarbone |
| 42 – 45 cm | 16 – 18" | Princess — just below the collarbone |
| 48 – 50 cm | 19 – 20" | Matinee — on the chest |
| 55 – 60 cm | 22 – 24" | Opera — mid-chest to sternum |
| 70 – 90 cm | 28 – 36" | Rope — below the bust, great for layering |
The string method
1
Cut a piece of string to the exact length of the necklace you are consideringFor example, cut 45 cm of string for a princess-length necklace.
2
Hold it around your neckPlace the string around your neck and hold the ends together at the front.
3
Check where it fallsLook in the mirror to see exactly where that length sits on your body. This is where your Zostma necklace will rest.
4
Adjust for pendantsIf your necklace has a pendant, it will hang slightly lower than where the string sits, as it adds a little extra drop.
Body proportions vary, so the string method is the most accurate way to visualise exactly where a necklace will fall on you specifically.
Layering necklaces? For a classic layered look, choose necklaces that differ by at least 5–7 cm in length. A great starting stack: 40 cm choker + 45 cm princess + 55 cm matinee. Mix different chain styles and pendant sizes for an editorial, high-jewellery feel.