Oh, no. Michele!
Someone drilled a hole in this beautiful coin from the old German State of Bavaria? Or, if not a hole, they put a crimp ring around it to make a necklace? Ugh. All of the collector value is gone. The only thing left is the bullion value, i.e., the value of its gold bullion.
Here are some pertinent statistics for these coins:
BAVARIA 10 Mark:
19 mm diameter
0.115 troy ounces gold
Approximate collector premium for well-preserved coins: $80
BAVARIA 20 Mark:
22 mm diameter
0.230 troy ounces gold
Approximate collector premium: $200
Collector premium for coins dated 1878: $800
The 20 Mark dated 1875 is the beast of the series; it catalogs at over $2000 in uncirculated condition.
You can use these statistics to estimate value of these coins. First, find the base value of the gold content by mulitplying the gold weight by the price of gold. Use a web site such as Kitco.com to find the price of gold. For instance, if gold is selling for $1400 US dollars per ounce, the base price of the 10 mark is $160 and of the 20 mark is $320. Second, add the collector premium to find an approximate retail price. The premium is zero for a damaged coin like Michele's, much lower for a worn or unappealing coin, and a little higher for a spectacular specimen.
A dealer would subtract or add a commission to the bullion value if he or she were buying or selling it, respectively.