The value of gemstones can extend over time. Especially precious are gemstones of the highest quality because they are rare and always in high demand.

In spite of the fact that their values increase over time there can occur instability in the appraisals of certain gemstones. This fluctuation depends on such factors as:
1. Supply and Demand

2. Individual Subjectivity

3. Type of Appraisal

Supply and Demand
Both supply and demand play an important role in the fluctuations of the value of gemstones. The supply-side value can increase in case if a gemstone has limited geographic sourcing like for example Tanzanite or Tsavorite. If supply suddenly discontinued (the flooding of the area and mine occured) but demand remained the same, it would mean that the value of these gemstones could raise significantly. The reverse could also lead to the same result, if a new mine and source located with abundant supply for a gemstone that has been in deficient supply before.

Individual Subjectivity
In most cases the appraiser’s individual preferences can have an impact on appraised value of a gemstone. Very often cut, color, clarity and carat weight determine the desirability of a given gemstone variety. Also the appraiser will decide the weighting of each of these four variables. For instance true- green Emeralds will be graded and valued by each appraiser higher than slightly bluish-green. However, the reverse may be also true for some appraisers.

Type of Appraisal
Replacement cost appraisals or insurance appraisals are provided in order to cover the person in case of the loss of property. So the value of the gemstones can increase because they should cover the replacement in a market that has unstable valuations.