I have seen claims on the internet saying sovereigns have face value of £1 and £100. These coins therefore have an embedded put option at the strike being the face value.
Here's the explanation from WikiPedia:
Britannia gold coins contain one troy ounce of gold and have a face value of £100. Gold Britannias also are issued in fractional sizes of one-half, one-quarter, and one-tenth of a troy ounce and with face values of £50, £25, and £10 respectively.
The sovereign is a gold coin of the United Kingdom, with a nominal value of one pound sterling. Prior to 1932 it was a fully circulating coin within Britain's then Gold Standard currency. Today it is used as a bullion coin and is sometimes mounted in jewelry.
I don't know how you'd have a put on something with higher actual value than face, because otherwise the same would be true with the American Eagle $20 and $50 coins.
The British gold Sovereign is one of, if not the most famous bullion coin in the world and was first introduced as long ago as 1489, under Henry VII. The coin has a face value of £1, although as an uncirculated bullion coin, a Sovereign’s real value is based on its pure gold content, which is worth considerably more than £1.
Since Britain abandoned the Gold Standard in 1931 the real value of the Sovereign has changed drastically, as the adoption of unbacked fiat currencies has completely altered the value of money. At the time of writing the real value of a full gold Sovereign is around £200. This is calculated by multiplying its pure gold content (7.3224g) by the gold spot price- currently around £27 per gram.
Of course, the fact that Sovereigns are considered to be semi-numismatic coins, a point of interest for coin collectors, means that certain Sovereigns will be worth even more than their bullion value. The demand for certain Sovereigns is boosted significantly by certain factors such as their rarity, the year or mint branch in which they were produced, or the specific design that they carry. While this is particularly interesting for collectors of certain Sovereigns, it must be noted that this does not necessarily make them intrinsically more valuable, as a bullion dealer will always value a bullion coin by its pure metal content.
from Bullion by post . com