Emeralds are considered to be extremely rare stones of the beryl family.  Emeralds can be light or dark green, bright green or the most desired color the young green grass hue.  All emerald contains inclusions.  The very expensive stones contain very faint inclusions barely visible to the naked eye.  the most common cut for this stone is the "emerald cut" but it also comes in oval cut, round and cabochon cuts.  The typical emerald color is virtually unmistakable.  Some atypical emeralds may display a olivine color. 

The biggest and most famous emeralds come from Columbia.  In today's market many emeralds originate from East Africa.  These stones have a quite strong color with a bluish-green tinge.  Stones of fine color (no matter their origin) weighing more that 2 carats are among the most highly valued gems and their price may exceed that of diamonds.

The  price of emeralds fall drastically as the size decreases and for those stones that are too dark or too pale.  Stones with too many inclusions and slightly turbid in color have a reduced  price.

Emeralds hardness ranges from 7.5 to 8 on the Moh's scale and it is also fairly brittle.  Owing to its brittleness emeralds can ship easy.  Care must be taken when wearing the stone, specially during high impact sports or during hard manual work.  Since they are softer than diamonds, rubies and sapphires emerald stones and jewelry should be stored separately.  

Because of the emerald's command a high price be aware of techniques used to hide a stone's flaws such as filling in cracks with oil tinted green a technique called "oiling".  Some experts consider this acceptable because they claim that it is good on stones with a brittle nature like emeralds.  However, if this treatment is done to a stone a reputable jeweler should tell the buyer this before the purchase is made.

Another treatment that is acceptable in the gem industry is to use epoxy resins.  However, both oiling and epoxy use on the stones make it harder for the buyer to determine if the price of the treated stone actually reflects the quality of the stone.  A good practice is to have an emerald purchase verified by a qualified gemologist-appraiser before the purchase is made.  Regrettably, because emeralds are highly desired gems that command very high prices it suffers from a greater occurrence of fraudulent practices.