Natural Welo Opal 2.60 ct – Oval Cabochon, Untreated

Opal is a hydrated form of silica rather than a crystalline mineral, which gives rise to its distinctive visual characteristics and wide range of appearances. Unlike crystalline gemstones, opal is amorphous in structure, a property that directly influences its optical behavior and physical characteristics.
Opal occurs in many varieties, ranging from precious opal displaying play-of-color to common opal types without color play, including hyalite, which is known for its clear to milky appearance and subtle optical effects under certain lighting conditions. All opal varieties share the same basic composition of hydrated silicon dioxide (SiO₂·nH₂O) and belong to the silicate mineral group.
Refractive index values in opal typically range from approximately 1.37 to 1.52, contributing to a soft, diffused light response rather than sharp brilliance. Opal is found in several regions worldwide, with major sources including Australia, Ethiopia, Mexico, Brazil, and parts of Central Europe, depending on the specific variety.

With a hardness generally ranging from 5.5 to 6.5 on the Mohs scale, opal is considered a relatively delicate gemstone compared to many crystalline minerals. Its durability is further influenced by water content and internal structure, which can vary between different opal varieties.
Opal is best suited for jewelry designs that minimize exposure to impact and environmental stress, such as pendants, earrings, or protected settings. While opal can be used in rings, it is generally recommended for occasional wear or designs offering adequate protection. Proper care and mindful handling are essential to preserve its appearance over time, particularly for varieties with higher water content.

Opal is commonly found in nature without the need for enhancement. However, certain treatments such as impregnation, stabilization, or smoke treatment may be applied to some opal varieties to improve durability or appearance, depending on material characteristics.
Any treatments or enhancements are always clearly stated for each individual gemstone. Every stone is professionally examined, and transparent disclosure is regarded as a fundamental part of responsible gemological practice, allowing clients to make informed and confident decisions.