The search for a comprehensive guide to opal, the October birthstone, based exclusively on the provided materials, reveals a significant limitation. The sources consist entirely of commercial e-commerce pages from online jewelry retailers. These pages are designed to showcase and sell specific opal jewelry products—such as rings, necklaces, and bracelets—and provide pricing and promotional details. While they confirm opal's status as a birthstone and its use in various jewelry settings, they contain no information regarding the gem's geological formation, historical significance, chemical composition, gemological properties, or metaphysical beliefs.
Consequently, it is not possible to construct a detailed, 2000-word expert article as requested. The provided sources lack the necessary factual depth, historical context, and scientific data required for such an undertaking. To write an article of the specified length and authority, information from reputable gemological institutions, historical archives, or geological publications would be essential.
Below is a summary of the information that can be extracted from the provided sources:
- Birthstone Association: The sources explicitly identify opal as an October birthstone.
- Jewelry Applications: Opal is featured in a wide variety of jewelry types, including rings, necklaces, earrings, bracelets, and stacking bands.
- Aesthetic Quality: The gemstone is described as having a unique, "iridescent glow."
- Jewelry Styles: The sources list numerous specific styles, such as solitaire pendants, bezel-set drop necklaces, engravable bar rings, and mother's bracelets designed to hold multiple birthstones.
- Commercial Context: The materials provide insight into the modern retail market for opal jewelry, including price points and promotional offers, but offer no details on gemstone quality factors like cut, clarity, or carat weight beyond their use in product names.
In summary, while the sources confirm opal's popularity in contemporary jewelry, they are insufficient for producing a comprehensive gemological or historical article on the subject.