Box set, 2 or 3.5 CTW Diamond Tennis Necklace set in 14K Gold.
Box setting is a squared off setting which makes the necklace look like one straight line of diamonds.
 12.5" diamonds with 3" extension for a total of 15.5". Lobster claw clasp makes this a "Multiway" adjustable necklace. Not only can you wear it at different lengths on your neck, it can also be wrapped twice around your wrist and worn as a double wrap tennis bracelet.  G-H color diamonds, SI2-I1 diamonds. 
This is THE style you want if you're looking for a yellow gold diamond tennis necklace under 5 carats.