18.75 Ct. Boulder Opal from Australia

As a gem specialist at The Natural Gemstone Company I am delighted to present this striking Boulder Opal, a semi translucent freeform gem weighing 18.75 carats. This piece measures 21.10 x 20.30 x 5.90 mm, and its generous size and freeform outline allow the vivid play of color to take center stage. The origin of this opal is Australia, and it displays the classic character of quality Australian boulder opal where vibrant opal seams rest against their natural ironstone matrix, which enhances durability and adds depth to the color presentation. The cut is not applicable in the traditional faceted sense, as this gem is fashioned with a freeform profile to preserve the most attractive areas of colour and pattern. The clarity grade is eye clean, evaluated at eye level, and the surface has been brought to an excellent polish. There has been no enhancement to this stone, making it a truly natural example of the material that collectors and designers prize.

Visually this Boulder Opal shows an intense color intensity, with a multi color palette that is dominated by deep oceanic blues and electric greens, with flashes that shift as the stone is viewed from different angles. The semi translucent body allows light to animate the internal structure, creating areas of brilliant fire that contrast beautifully with darker, more mysterious patches of color, producing a lively and dynamic appearance. Because it is a freeform cut rather than a standard faceted or cabochon shape, the gem retains organic lines and a unique silhouette that will make any finished piece feel bespoke. The excellent polish enhances surface luster and smoothness, and the eye clean clarity ensures that the color fields remain uninterrupted at normal viewing distances. As a boulder opal the stone benefits from a natural ironstone backing in portions, which provides structural support and allows for secure settings without the need for synthetic backing or stabilization. This makes it well suited for a variety of jewelry applications, including bespoke rings, pendants, or sculptural brooch designs, where the setting can be crafted to showcase the most vivid color zones while protecting the edges and thinner areas.

When selecting this Boulder Opal from The Natural Gemstone Company you are choosing a fully natural, untreated gemstone with documented Australian origin and fine lapidary finishing. For jewelry design I often recommend settings that cradle the stone on the sides and back, while allowing the face to receive light and movement, such as custom bezels with a slight lift or open backed bezels where the natural ironstone support is preserved. For a statement ring I suggest a low profile bezel to protect the table and edges, paired with a simple band to let the opal remain the focal point. For a pendant a thin bezel with hidden prongs can secure the stone while allowing light to interact with its play of color. We can provide professional recommendations for mounting and can arrange custom work through our trusted partners if you wish to commission a finished piece. Care is simple, keep the opal away from prolonged exposure to harsh chemicals and extreme heat, avoid ultrasonic cleaners, and store it separately to prevent abrasion. At The Natural Gemstone Company we stand behind the authenticity and quality of this piece, and we offer clear communication about origin, weight, measurements, clarity grade, color intensity, polish, and the fact that there are no enhancements. If you would like additional images, lighting views, or assistance in selecting a setting that complements the unique shape and colors of this 18.75 carat Boulder Opal, please contact us and we will be pleased to assist you in creating a treasured piece that highlights the natural beauty of this exceptional Australian gem.