[mgolawala]

How is the exchange rate between modern money and "carolus guilders" calculated?

Something like a foreign exchange market cannot help determine this right?

In theory, could the exchange rate for $1 be made equal to 1,200 carolus guilders? (Effectively, making the bonds worthless)

[crote]

There's a pretty continuous line between the carolus guilder and the euro. For example, the modern-day (2002) guilder was fixed at an exchange rate of 2.2 GLD = 1 EUR. Previous coins also had a more-or-less fixed ratio, aided by the value of the gold and/or silver they were made out of.

If you want to treat it like a completely separate coin, you'd have to buy historical carolus guilders in auctions. They seem to be worth about €1500 [0], although the same amount of gold can be bought for only €240.

[0]: https://www.ma-shops.nl/henzen/item.php?id=77815

[comradesmith]

It would be done stepwise.

When the Dutch florin was introduced there would have been an agreed (or imposed) exchange rate. Looks like that was 1:1.

Later when the Euro was adopted there was an exchange rate for that too.

To get to USD use the floating exchange rate of the open market.

[lesuorac]

I guess conversely, if you had a bond dominated in say Francs and the currency goes away do you just default?

[crote]

Currencies rarely "go away". They are usually replaced by new ones, and the government will buy the old currency and pay you in new currency. Imagine the mayhem if a government decided that all money everyone owned would suddenly be completely worthless!

[evanb]

In 2016 India demonetized some bank notes (true, not the whole currency)

https://en.wikipedia.org/wiki/2016_Indian_banknote_demonetis...