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Home Gemstones Onyx
4.20 ct Black Onyx Gemstone, Onyx Gem in Heart Rose-Cut Shape for Sale.
Photos are of Actual Product for Sale
4.20 ct Black Onyx Stone, Natural Onyx in Heart Rose-Cut Shape for Sale Onyx Gemstone in 10 x 10 mm (calibrated) Size for Sale, Onyx Stone in Black Color

4.20ct Natural Black Onyx, Heart Shape, 10.3x10.3 mm

9.7 out of 10
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Product ID: 721337
Type: Onyx
Weight: 4.20 ct 1 gem
Size: 10 x 10 mm calibrated
Size: 10.3 x 10.3 x 5 mm
Exact Size: 10.33 x 10.27 x 5.02 mm
Length x Width x Depth
Shape: Heart Rose-Cut
Color: Black
Clarity: Opaque
Treatment: Dyed
Origin: Sri Lanka
Content: 1 pc
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Product Description

This is a 4.20 carat natural black Onyx gem, 1 pc in heart shape with an exact size of 10.33 x 10.27 x 5.02 mm. This loose Onyx gemstone was mined in Sri Lanka and its clarity is Opaque.

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GemSelect Certified Store Reviews

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Overall Rating -> 10 star ratings

Easy process.

Posted By Crafty Seabee in March, 2026
Source: Bizrate

Overall Rating -> 9 star ratings

Fast snd easy to find what I was looking for

Posted By Bawb in May, 2026
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Overall Rating -> 10 star ratings

I have shopped at Gemselect for nearly 20 years. I especially like that you see pictures of the exact gem you are purchasing. You are a trusted source.

Posted By DNaber in October, 2025
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Overall Rating -> 10 star ratings

On the clarity options it goes "and better" so if youre looking for si specifically and you click si and better it still shows you basically everything. It just removes the opaques. Itd be nice if it was vs only, vss only, si only, etc

Posted By Iamnotakrustykrab in December, 2025
Source: Bizrate

Overall Rating -> 10 star ratings

I needed a very specific color of tourmaline and Gem Select had it. I had to get the client to agree and then ordered the stone. It arrived better than pictured and we all were very happy.

Posted By Tim W in February, 2026
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Overall Rating -> 10 star ratings

Great site for finding specific stones and sizes for individual pieces of jewelry

Posted By Designer in December, 2025
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