search
  • Sign In
    Sign Up
  • English speaking customer support only

    1-800-464-1640

    International:

    +66-39601289

  • Change Language
  • USD
  • CART
FREE SHIPPING

Buy 16 - 18 mm Boulder Opal Gems

(25)
16 - 18 mm Boulder Opal Gems Weight 16 - 18 mm Boulder Opal Gems Size 16 - 18 mm Boulder Opal Gems Clarity 16 - 18 mm Boulder Opal Gems Price 16 - 18 mm Boulder Opal Gems Origin
More
16 - 18 mm Boulder Opal Gems Single
16 - 18 mm Boulder Opal Gems Pairs
16 - 18 mm Boulder Opal Gems Lots
16 - 18 mm Boulder Opal Gems Faceted
16 - 18 mm Boulder Opal Gems Cabochons
Sort By:
Clear All
Photos are of Actual Products for Sale

5.29 ct Fancy Boulder Opal, 17.4 x 12.2 mm From Australia

Natural Boulder Opal, Qty: 1 pc | 5.29 carat weight Boulder Opal

5.29ct1 Piece
$ 26.45
17.4 x 12.2 mm
Item Description
Stone Type: Loose Boulder Opal
Boulder Opal Weight: 5.29 ct Boulder Opal
Boulder Opal Shape: Fancy Cabochon Boulder Opal
Boulder Opal Size: 17.4 x 12.2 mm Boulder Opal
Boulder Opal Color: Multicolor Boulder Opal
Boulder Opal Clarity: Opaque Boulder Opal
Boulder Opal Origin: Australia Boulder Opal
Boulder Opal Treatment: Untreated
Boulder Opal Quantity: 1
Boulder Opal Certificate: GemSelect
Product Description:
View Details
Add to Cart

7.88 ct Oval Boulder Opal, 16.8 x 11.6 mm From Australia

Natural Boulder Opal, Qty: 1 pc | 7.88 carat weight Boulder Opal

7.88ct1 Piece
$ 39.40
16.8 x 11.6 mm
Item Description
Stone Type: Loose Boulder Opal
Boulder Opal Weight: 7.88 ct Boulder Opal
Boulder Opal Shape: Oval Cabochon Boulder Opal
Boulder Opal Size: 16.8 x 11.6 mm Boulder Opal
Boulder Opal Color: Multicolor Boulder Opal
Boulder Opal Clarity: Opaque Boulder Opal
Boulder Opal Origin: Australia Boulder Opal
Boulder Opal Treatment: Untreated
Boulder Opal Quantity: 1
Boulder Opal Certificate: GemSelect
Product Description:
View Details
Add to Cart

11.24 ct Fancy Boulder Opal, 16.7 x 13.8 mm From Australia

Natural Boulder Opal, Qty: 1 pc | 11.24 carat weight Boulder Opal

11.24ct1 Piece
$ 56.20
16.7 x 13.8 mm
Item Description
Stone Type: Loose Boulder Opal
Boulder Opal Weight: 11.24 ct Boulder Opal
Boulder Opal Shape: Fancy Cabochon Boulder Opal
Boulder Opal Size: 16.7 x 13.8 mm Boulder Opal
Boulder Opal Color: Multicolor Boulder Opal
Boulder Opal Clarity: Opaque Boulder Opal
Boulder Opal Origin: Australia Boulder Opal
Boulder Opal Treatment: Untreated
Boulder Opal Quantity: 1
Boulder Opal Certificate: GemSelect
Product Description:
View Details
Add to Cart

6.9 ct Fancy Boulder Opal, 16.1 x 12.5 mm From Australia

Natural Boulder Opal, Qty: 1 pc | 6.90 carat weight Boulder Opal

6.90ct1 Piece
$ 34.50
16.1 x 12.5 mm
Item Description
Stone Type: Loose Boulder Opal
Boulder Opal Weight: 6.90 ct Boulder Opal
Boulder Opal Shape: Fancy Cabochon Boulder Opal
Boulder Opal Size: 16.1 x 12.5 mm Boulder Opal
Boulder Opal Color: Multicolor Boulder Opal
Boulder Opal Clarity: Opaque Boulder Opal
Boulder Opal Origin: Australia Boulder Opal
Boulder Opal Treatment: Untreated
Boulder Opal Quantity: 1
Boulder Opal Certificate: GemSelect
Product Description:
View Details
Add to Cart

6.16 ct Fancy Boulder Opal, 16.7 x 9.7 mm From Australia

Natural Boulder Opal, Qty: 1 pc | 6.16 carat weight Boulder Opal

6.16ct1 Piece
$ 30.80
16.7 x 9.7 mm
Item Description
Stone Type: Loose Boulder Opal
Boulder Opal Weight: 6.16 ct Boulder Opal
Boulder Opal Shape: Fancy Cabochon Boulder Opal
Boulder Opal Size: 16.7 x 9.7 mm Boulder Opal
Boulder Opal Color: Multicolor Boulder Opal
Boulder Opal Clarity: Opaque Boulder Opal
Boulder Opal Origin: Australia Boulder Opal
Boulder Opal Treatment: Untreated
Boulder Opal Quantity: 1
Boulder Opal Certificate: GemSelect
Product Description:
View Details
Add to Cart

9.92 ct Fancy Boulder Opal, 17.4 x 15.5 mm From Australia

Natural Boulder Opal, Qty: 1 pc | 9.92 carat weight Boulder Opal

9.92ct1 Piece
$ 49.60
17.4 x 15.5 mm
Item Description
Stone Type: Loose Boulder Opal
Boulder Opal Weight: 9.92 ct Boulder Opal
Boulder Opal Shape: Fancy Cabochon Boulder Opal
Boulder Opal Size: 17.4 x 15.5 mm Boulder Opal
Boulder Opal Color: Multicolor Boulder Opal
Boulder Opal Clarity: Opaque Boulder Opal
Boulder Opal Origin: Australia Boulder Opal
Boulder Opal Treatment: Untreated
Boulder Opal Quantity: 1
Boulder Opal Certificate: GemSelect
Product Description:
View Details
Add to Cart

6.1 ct Fancy Boulder Opal, 17 x 11.5 mm From Australia

Natural Boulder Opal, Qty: 1 pc | 6.10 carat weight Boulder Opal

6.10ct1 Piece
$ 30.50
17 x 11.5 mm
Item Description
Stone Type: Loose Boulder Opal
Boulder Opal Weight: 6.10 ct Boulder Opal
Boulder Opal Shape: Fancy Cabochon Boulder Opal
Boulder Opal Size: 17 x 11.5 mm Boulder Opal
Boulder Opal Color: Multicolor Boulder Opal
Boulder Opal Clarity: Transparent Boulder Opal
Boulder Opal Origin: Australia Boulder Opal
Boulder Opal Treatment: Untreated
Boulder Opal Quantity: 1
Boulder Opal Certificate: GemSelect
Product Description:
View Details
Add to Cart

14.15 ct Fancy Boulder Opal, 17.9 x 14.9 mm From Australia

Natural Boulder Opal, Qty: 1 pc | 14.15 carat weight Boulder Opal

14.15ct1 Piece
$ 70.75
17.9 x 14.9 mm
Item Description
Stone Type: Loose Boulder Opal
Boulder Opal Weight: 14.15 ct Boulder Opal
Boulder Opal Shape: Fancy Cabochon Boulder Opal
Boulder Opal Size: 17.9 x 14.9 mm Boulder Opal
Boulder Opal Color: Multicolor Boulder Opal
Boulder Opal Clarity: Opaque Boulder Opal
Boulder Opal Origin: Australia Boulder Opal
Boulder Opal Treatment: Untreated
Boulder Opal Quantity: 1
Boulder Opal Certificate: GemSelect
Product Description:
View Details
Add to Cart

11.57 ct Oval Boulder Opal, 17.3 x 12.3 mm From Australia

Natural Boulder Opal, Qty: 1 pc | 11.57 carat weight Boulder Opal

11.57ct1 Piece
$ 80.99
17.3 x 12.3 mm
Item Description
Stone Type: Loose Boulder Opal
Boulder Opal Weight: 11.57 ct Boulder Opal
Boulder Opal Shape: Oval Cabochon Boulder Opal
Boulder Opal Size: 17.3 x 12.3 mm Boulder Opal
Boulder Opal Color: Multicolor Boulder Opal
Boulder Opal Clarity: Opaque Boulder Opal
Boulder Opal Origin: Australia Boulder Opal
Boulder Opal Treatment: Untreated
Boulder Opal Quantity: 1
Boulder Opal Certificate: GemSelect
Product Description:
View Details
Add to Cart
9.46ct1 Piece
$ 66.22
17.9 x 12 mm
Item Description
Stone Type: Loose Boulder Opal
Boulder Opal Weight: 9.46 ct Boulder Opal
Boulder Opal Shape: Pear Cabochon Boulder Opal
Boulder Opal Size: 17.9 x 12 mm Boulder Opal
Boulder Opal Color: Multicolor Boulder Opal
Boulder Opal Clarity: Opaque Boulder Opal
Boulder Opal Origin: Australia Boulder Opal
Boulder Opal Treatment: Untreated
Boulder Opal Quantity: 1
Boulder Opal Certificate: GemSelect
Product Description:
View Details
Add to Cart

5.28 ct Trillion Boulder Opal, 17.3 x 15.9 mm From Australia

Natural Boulder Opal, Qty: 1 pc | 5.28 carat weight Boulder Opal

5.28ct1 Piece
$ 36.96
17.3 x 15.9 mm
Item Description
Stone Type: Loose Boulder Opal
Boulder Opal Weight: 5.28 ct Boulder Opal
Boulder Opal Shape: Trillion Cabochon Boulder Opal
Boulder Opal Size: 17.3 x 15.9 mm Boulder Opal
Boulder Opal Color: Multicolor Boulder Opal
Boulder Opal Clarity: Translucent Boulder Opal
Boulder Opal Origin: Australia Boulder Opal
Boulder Opal Treatment: Untreated
Boulder Opal Quantity: 1
Boulder Opal Certificate: GemSelect
Product Description:
View Details
Add to Cart
7.48ct1 Piece
$ 52.36
16.5 x 11.8 mm
Item Description
Stone Type: Loose Boulder Opal
Boulder Opal Weight: 7.48 ct Boulder Opal
Boulder Opal Shape: Pear Cabochon Boulder Opal
Boulder Opal Size: 16.5 x 11.8 mm Boulder Opal
Boulder Opal Color: Multicolor Boulder Opal
Boulder Opal Clarity: Opaque Boulder Opal
Boulder Opal Origin: Australia Boulder Opal
Boulder Opal Treatment: Untreated
Boulder Opal Quantity: 1
Boulder Opal Certificate: GemSelect
Product Description:
View Details
Add to Cart

7.58 ct Fancy Boulder Opal, 18 x 9.2 mm From Australia

Natural Boulder Opal, Qty: 1 pc | 7.58 carat weight Boulder Opal

7.58ct1 Piece
$ 37.90
18 x 9.2 mm
Item Description
Stone Type: Loose Boulder Opal
Boulder Opal Weight: 7.58 ct Boulder Opal
Boulder Opal Shape: Fancy Cabochon Boulder Opal
Boulder Opal Size: 18 x 9.2 mm Boulder Opal
Boulder Opal Color: Multicolor Boulder Opal
Boulder Opal Clarity: Opaque Boulder Opal
Boulder Opal Origin: Australia Boulder Opal
Boulder Opal Treatment: Untreated
Boulder Opal Quantity: 1
Boulder Opal Certificate: GemSelect
Product Description:
View Details
Add to Cart

14.37 ct Oval Boulder Opal, 16.4 x 13.1 mm From Australia

Natural Boulder Opal, Qty: 1 pc | 14.37 carat weight Boulder Opal

14.37ct1 Piece
$ 100.59
16.4 x 13.1 mm
Item Description
Stone Type: Loose Boulder Opal
Boulder Opal Weight: 14.37 ct Boulder Opal
Boulder Opal Shape: Oval Cabochon Boulder Opal
Boulder Opal Size: 16.4 x 13.1 mm Boulder Opal
Boulder Opal Color: Multicolor Boulder Opal
Boulder Opal Clarity: Opaque Boulder Opal
Boulder Opal Origin: Australia Boulder Opal
Boulder Opal Treatment: Untreated
Boulder Opal Quantity: 1
Boulder Opal Certificate: GemSelect
Product Description:
View Details
Add to Cart

8.06 ct Oval Boulder Opal, 16.8 x 11.8 mm From Australia

Natural Boulder Opal, Qty: 1 pc | 8.06 carat weight Boulder Opal

8.06ct1 Piece
$ 62.06
16.8 x 11.8 mm
Item Description
Stone Type: Loose Boulder Opal
Boulder Opal Weight: 8.06 ct Boulder Opal
Boulder Opal Shape: Oval Cabochon Boulder Opal
Boulder Opal Size: 16.8 x 11.8 mm Boulder Opal
Boulder Opal Color: Multicolor Boulder Opal
Boulder Opal Clarity: Opaque Boulder Opal
Boulder Opal Origin: Australia Boulder Opal
Boulder Opal Treatment: Untreated
Boulder Opal Quantity: 1
Boulder Opal Certificate: GemSelect
Product Description:
View Details
Add to Cart

12.73 ct Trillion Boulder Opal, 16.6 x 15.7 mm From Australia

Natural Boulder Opal, Qty: 1 pc | 12.73 carat weight Boulder Opal

12.73ct1 Piece
$ 63.65
16.6 x 15.7 mm
Item Description
Stone Type: Loose Boulder Opal
Boulder Opal Weight: 12.73 ct Boulder Opal
Boulder Opal Shape: Trillion Cabochon Boulder Opal
Boulder Opal Size: 16.6 x 15.7 mm Boulder Opal
Boulder Opal Color: Multicolor Boulder Opal
Boulder Opal Clarity: Opaque Boulder Opal
Boulder Opal Origin: Australia Boulder Opal
Boulder Opal Treatment: Untreated
Boulder Opal Quantity: 1
Boulder Opal Certificate: GemSelect
Product Description:
View Details
Add to Cart

9.35 ct Fancy Boulder Opal, 17.6 x 14.2 mm From Australia

Natural Boulder Opal, Qty: 1 pc | 9.35 carat weight Boulder Opal

9.35ct1 Piece
$ 46.75
17.6 x 14.2 mm
Item Description
Stone Type: Loose Boulder Opal
Boulder Opal Weight: 9.35 ct Boulder Opal
Boulder Opal Shape: Fancy Cabochon Boulder Opal
Boulder Opal Size: 17.6 x 14.2 mm Boulder Opal
Boulder Opal Color: Multicolor Boulder Opal
Boulder Opal Clarity: Opaque Boulder Opal
Boulder Opal Origin: Australia Boulder Opal
Boulder Opal Treatment: Untreated
Boulder Opal Quantity: 1
Boulder Opal Certificate: GemSelect
Product Description:
View Details
Add to Cart

12.53 ct Oval Boulder Opal, 17.8 x 13.7 mm From Australia

Natural Boulder Opal, Qty: 1 pc | 12.53 carat weight Boulder Opal

12.53ct1 Piece
$ 62.65
17.8 x 13.7 mm
Item Description
Stone Type: Loose Boulder Opal
Boulder Opal Weight: 12.53 ct Boulder Opal
Boulder Opal Shape: Oval Cabochon Boulder Opal
Boulder Opal Size: 17.8 x 13.7 mm Boulder Opal
Boulder Opal Color: Multicolor Boulder Opal
Boulder Opal Clarity: Opaque Boulder Opal
Boulder Opal Origin: Australia Boulder Opal
Boulder Opal Treatment: Untreated
Boulder Opal Quantity: 1
Boulder Opal Certificate: GemSelect
Product Description:
View Details
Add to Cart

10.97 ct Cushion Boulder Opal, 17 x 11.4 mm From Australia

Natural Boulder Opal, Qty: 1 pc | 10.97 carat weight Boulder Opal

10.97ct1 Piece
$ 54.85
17 x 11.4 mm
Item Description
Stone Type: Loose Boulder Opal
Boulder Opal Weight: 10.97 ct Boulder Opal
Boulder Opal Shape: Cushion Cabochon Boulder Opal
Boulder Opal Size: 17 x 11.4 mm Boulder Opal
Boulder Opal Color: Multicolor Boulder Opal
Boulder Opal Clarity: Opaque Boulder Opal
Boulder Opal Origin: Australia Boulder Opal
Boulder Opal Treatment: Untreated
Boulder Opal Quantity: 1
Boulder Opal Certificate: GemSelect
Product Description:
View Details
Add to Cart

11.65 ct Round Boulder Opal, 17 mm From Australia

Natural Boulder Opal, Qty: 1 pc | 11.65 carat weight Boulder Opal

11.65ct1 Piece
$ 81.55
17 mm
Item Description
Stone Type: Loose Boulder Opal
Boulder Opal Weight: 11.65 ct Boulder Opal
Boulder Opal Shape: Round Cabochon Boulder Opal
Boulder Opal Size: 17 mm Boulder Opal
Boulder Opal Color: Multicolor Boulder Opal
Boulder Opal Clarity: Opaque Boulder Opal
Boulder Opal Origin: Australia Boulder Opal
Boulder Opal Treatment: Untreated
Boulder Opal Quantity: 1
Boulder Opal Certificate: GemSelect
Product Description:
View Details
Add to Cart

7.85 ct Fancy Boulder Opal, 16.4 x 11.8 mm From Australia

Natural Boulder Opal, Qty: 1 pc | 7.85 carat weight Boulder Opal

7.85ct1 Piece
$ 54.95
16.4 x 11.8 mm
Item Description
Stone Type: Loose Boulder Opal
Boulder Opal Weight: 7.85 ct Boulder Opal
Boulder Opal Shape: Fancy Cabochon Boulder Opal
Boulder Opal Size: 16.4 x 11.8 mm Boulder Opal
Boulder Opal Color: Multicolor Boulder Opal
Boulder Opal Clarity: Opaque Boulder Opal
Boulder Opal Origin: Australia Boulder Opal
Boulder Opal Treatment: Untreated
Boulder Opal Quantity: 1
Boulder Opal Certificate: GemSelect
Product Description:
View Details
Add to Cart

11.36 ct Cushion Boulder Opal, 17.5 x 11.4 mm From Australia

Natural Boulder Opal, Qty: 1 pc | 11.36 carat weight Boulder Opal

11.36ct1 Piece
$ 56.80
17.5 x 11.4 mm
Item Description
Stone Type: Loose Boulder Opal
Boulder Opal Weight: 11.36 ct Boulder Opal
Boulder Opal Shape: Cushion Cabochon Boulder Opal
Boulder Opal Size: 17.5 x 11.4 mm Boulder Opal
Boulder Opal Color: Multicolor Boulder Opal
Boulder Opal Clarity: Opaque Boulder Opal
Boulder Opal Origin: Australia Boulder Opal
Boulder Opal Treatment: Untreated
Boulder Opal Quantity: 1
Boulder Opal Certificate: GemSelect
Product Description:
View Details
Add to Cart

21.39 ct Cushion Boulder Opal, 16.4 x 16.4 mm From Australia

Natural Boulder Opal, Qty: 1 pc | 21.39 carat weight Boulder Opal

21.39ct1 Piece
$ 164.70
16.4 x 16.4 mm
Item Description
Stone Type: Loose Boulder Opal
Boulder Opal Weight: 21.39 ct Boulder Opal
Boulder Opal Shape: Cushion Cabochon Boulder Opal
Boulder Opal Size: 16.4 x 16.4 mm Boulder Opal
Boulder Opal Color: Multicolor Boulder Opal
Boulder Opal Clarity: Opaque Boulder Opal
Boulder Opal Origin: Australia Boulder Opal
Boulder Opal Treatment: Untreated
Boulder Opal Quantity: 1
Boulder Opal Certificate: GemSelect
Product Description:
View Details
Add to Cart

39.95 ct Drilled Sphere Boulder Opal, 17.6 mm From Australia

Natural Boulder Opal, Qty: 1 pc | 39.95 carat weight Boulder Opal

39.95ct1 Piece
$ 199.75
17.6 mm
Item Description
Stone Type: Loose Boulder Opal
Boulder Opal Weight: 39.95 ct Boulder Opal
Boulder Opal Shape: Drilled Sphere Boulder Opal
Boulder Opal Size: 17.6 mm Boulder Opal
Boulder Opal Color: Multicolor Boulder Opal
Boulder Opal Clarity: Opaque Boulder Opal
Boulder Opal Origin: Australia Boulder Opal
Boulder Opal Treatment: Untreated
Boulder Opal Quantity: 1
Boulder Opal Certificate: GemSelect
Product Description:
View Details
Add to Cart
7.81ct1 Piece
$ 60.14
16.4 x 10.5 mm
Item Description
Stone Type: Loose Boulder Opal
Boulder Opal Weight: 7.81 ct Boulder Opal
Boulder Opal Shape: Pear Cabochon Boulder Opal
Boulder Opal Size: 16.4 x 10.5 mm Boulder Opal
Boulder Opal Color: Multicolor Boulder Opal
Boulder Opal Clarity: Opaque Boulder Opal
Boulder Opal Origin: Australia Boulder Opal
Boulder Opal Treatment: Untreated
Boulder Opal Quantity: 1
Boulder Opal Certificate: GemSelect
Product Description:
View Details
Add to Cart
Read All

Over 19 Years in the Gemstone Business!

Thank you for trusting us with your purchase!

Overall Rating -> 10 star ratings

I love GemSelect, photos and details are great.

Posted By #1 in February, 2024
Source: Bizrate

Overall Rating -> 9 star ratings

It went well

Posted By Rob in December, 2023
Source: Bizrate

Overall Rating -> 10 star ratings

I really enjoy browsing through GemSelect. The selection is always marvelous and I love how detailed everything is described. The only thing I noticed is that when browsing through my phone, the videos of the gems do not load. If there were more videos of the gems, that would be amazing, though I understand that is a lot of work on GemSelect's part! Checking out is also very fast and easy, and I love that the return policy is very good, though I hope I don't have to use it anytime soon.

Posted By ChiChi in January, 2024
Source: Bizrate

Overall Rating -> 10 star ratings

Easy to find the stones I was looking for. Always good quality stones

Posted By Erin in June, 2023
Source: Bizrate

Overall Rating -> 10 star ratings

Easy to use.

Posted By Hope in March, 2024
Source: Bizrate

Overall Rating -> 10 star ratings

it was good

Posted By Bobk in January, 2024
Source: Bizrate

Overall Rating -> 10 star ratings

Everything fine.

Posted By Hilario in December, 2023
Source: Bizrate

Overall Rating -> 10 star ratings

Overall, the whole process was just great.

Posted By Thatoneguy in August, 2023
Source: Bizrate

Overall Rating -> 9 star ratings

Good interaction with site

Posted By Brick in September, 2023
Source: Bizrate

Overall Rating -> 10 star ratings

I really enjoy browsing through GemSelect. The selection is always marvelous and I love how detailed everything is described. The only thing I noticed is that when browsing through my phone, the videos of the gems do not load. If there were more videos of the gems, that would be amazing, though I understand that is a lot of work on GemSelect's part! Checking out is also very fast and easy, and I love that the return policy is very good, though I hope I don't have to use it anytime soon.

Posted By ChiChi in January, 2024
Source: Bizrate

Overall Rating -> 10 star ratings

I have used Gem Select many times over the past 10 years and have always been happy with the product & services

Posted By Ordain in August, 2023
Source: Bizrate

Overall Rating -> 10 star ratings

i love this site, the gems are always of good quality, i've been buy gifts from the site for 10 years, love it

Posted By Jf in January, 2024
Source: Bizrate

Overall Rating -> 10 star ratings

Very detailed and great pictures

Posted By Alexandrite in November, 2023
Source: Bizrate

Overall Rating -> 10 star ratings

The website is easy to navigate and the images are incredible.

Posted By Lindsy in October, 2023
Source: Bizrate

Overall Rating -> 9 star ratings

Not easy enough to buy by exact size, and many stones aren't carbechon curved shape on top

Posted By Erick in July, 2023
Source: Bizrate
STAY IN TOUCH | NEWSLETTER
*You're signing up to receive GemSelect promotional email.
Partners and Trust Payment options

Switch to Mobile Version

Copyright © 2005-2024 GemSelect.com all rights reserved.

Reproduction (text or graphics) without the express written consent of GemSelect.com (SETT Company Ltd.) is strictly prohibited.

7604

Continue Shopping
Checkout
Continue Shopping
Checkout