Oval Dominican larimar cabochon, 25 x 18 mm. Standard format for the lapidary market: compatible with cocktail ring settings, central pendant, and 925 silver brooch without the need for adjustment.
Item details
| Mineral |
Larimar (blue pectolite: NaCa2Si3O8(OH) with traces of Cu) |
| Dimensions |
25 x 18 mm (±0.5 mm); approximate height 5–8 mm |
| Shape and back |
Oval; flat back |
| Finish |
Mirror polished |
| Hardness |
4.5–5 Mohs — we recommend closed bezel setting in 925 silver |
| Origin |
Dominican Republic (Sierra de Bahoruco, Barahona province) |
| Treatment |
Untreated |
| Item type |
Calibrated commercial stock; unique vein pattern in each piece |
This specific piece
The 25 x 18 mm format is the most requested standard size for commercial cocktail ring and statement pendant settings.
The pattern of white veins on turquoise blue is unique in each piece: no two are alike even if they share the same dimensions. In some pieces, the pattern evokes parallel waves; in others, nebulous spots or angular figures.
Larimar: the exclusive mineral of the Sierra de Bahoruco
Blue pectolite — larimar — is chemically NaCa2Si3O8(OH) with traces of copper replacing calcium and creating the blue color. It only forms in the specific geological context of a volcanic vein in the province of Barahona, Dominican Republic.
For which mounting it works
-
Oval closed bezel in 925 silver — The bezel for 25 x 18 mm is a standard size available in jewelry component catalogs, which greatly facilitates the work. With Mohs 4.5–5, the bezel is the only recommended mounting to protect the edge. Oxidized or polished 925 silver in finishes contrasting with the blue.
-
Statement cocktail ring — The 25 x 18 mm format is exactly the classic size of an occasion statement ring. The oval symmetry allows the stone to be oriented both longitudinally and transversely depending on the design.
-
Central pendant for long chain — The 25 x 18 mm oval with a long drop is one of the most requested formats in designer jewelry. The size is large enough to make a statement without being excessive.
Larimar in the tradition of crystals
The geographical exclusivity of larimar — unique to one point on the planet — has contributed to its mythology. It is called "Caribbean stone," "Atlantis stone," or "sea stone."
The symbolic associations attributed to minerals belong to cultural and historical traditions. They are shared for educational purposes, not as medical advice.
How to recognize authentic larimar
Opaque, with a waxy to vitreous luster. The white veins have a natural pattern of waves, spots, or angular figures — never artificially regular. Under magnification, the microcrystalline texture is fine with no bubbles.
Frequently asked questions
Are the 25 x 18 mm dimensions exact for prefabricated settings?
Yes, with a tolerance of ±0.5 mm. Most catalog settings for 25 x 18 mm accommodate this variation. We recommend verifying the dimensions of the specific piece before ordering a custom setting.
Is this larimar treated?
No detectable treatment. Statement based on lapidary observation; the piece does not include formal gemological certification. The blue color is intrinsic to the mineral.
Why does the color vary between pieces of the same size?
The 25 x 18 mm format is dimensionally calibrated, but the pattern and blue tone depend on the area of the vein from which each piece comes. This variability is inherent to natural larimar; there is no color-calibrated larimar.
Is it suitable for daily wear rings?
With Mohs 4.5–5, larimar is fragile compared to quartz (Mohs 7) or sapphire (Mohs 9). In daily wear rings, the risk of scratching and chipping is real. We recommend reserving it for occasional use or cocktail rings that are not worn during manual work.
What is the dimensional tolerance?
±0.5 mm in length and width. The height can vary more between pieces from the same lot.
How to care for it?
Avoid ultrasonic cleaners, steam, and prolonged sun exposure. Clean with a soft cloth and warm water. See the guide on jewelry care.
See also: cabochon collection | rings.
