Sad to say, Jade (and Raven), your coin looks fake. The surfaces look very un-natural. To see pictures of genuine cobs, check this page:
This page gives a comprehensive summary of Spanish Colonial coins. Near the bottom, you will see photos of genuine cob coins.
Hi Mark --
I'm impressed with the 14 inches (and with the Coca Cola!). But I still think your coin, and the one on the Collector's Weekly site, are fakes. Hope I'm wrong.
A big distinguishing feature on your coin is the large "S" on the shield side. This means Seville, Spain. The database I use has 39 genuine coins like this. My first picture is a real beauty.
My next two pictures show your coin and the CW coin on either side of another database genuine. There is really no comparison.
Here is the auction description for the coin in my first picture. (BTW, Daniel Sedwick is the defacto expert on these coins. Check out his web site).
Daniel Frank Sedwick, LLC > Auction 9 Auction date: 26 April 2011
Lot number: 1293
Price realized: 500 USD (Approx. 342 EUR / 304 GBP / 440 CHF)
Seville, Spain, cob 4 reales, Philip II, assayer Gothic D outside tressure at 4 and 8 o'clock (pre-1588). 13.6 grams. CT-393.
Choice XF with lovely rich toning all over, perfect full cross-and-tressure, crown and shield, bold S to left and denomination o-IIII to right, nearly full legends, quite attractive.
Tabitha -- These coins are very difficult to authenticate. You can post pictures here and we will give opinions. The de-facto expert on coins like this is Daniel Sedwick, here: