The ascribed value to a gemstone will always be based on the 4C's:
Color – A pure gemstone would contain no hue outside of the intended color. The ideal diamond would be absent of coloring.
Cut – Cut grade is determined by how well it transmits light. The trademark sparkle of a gemstone is a result of how well the stone interacts with the light based on the cut.
Clarity – Natural gemstones are formed when a material (e.g. carbon: diamonds; alumina: rubies; beryllium: emeralds) is exposed to tremendous heat and pressure. The process will typically result in internal 'inclusions' and external 'blemishes'. A pure gemstone is most certainly a rarity but the closer to pure the higher the value.
Carat Weight – Carat is the term used to quantify a gemstone's weight. A carat represents 200 milligrams. A larger carat weight is more valuable and less common.
High-end jewelry will often be marked with the 'signature' of the maker. The condition of the piece itself, the condition of the signature, and the setting will all affect an Eliasson appraisal.
When submitting jewelry for appraisal please include: a detailed description of the piece, a photograph of the item, and any background information available.