Coins from Nepal are sure to be among the next ***big risers*** in coin collecting. They are unusual and super-interesting, and the one from Kellie is made of silver, so that's good.
Coins with the pattern shown come from the era of Trihuvana Bir Bikram, but the same pattern is used on-and-off for several years after that, up to 1991. Both rupees and 50 paisa coins have the same pattern. You must tell them apart by their size.
You have to know two things to transform the coin's date to a Western (Gregorian) date. First, you have to know the numeric characters, shown here. (There are others found on Nepalese coins which are not in our figure.) Then you have to know that Nepalese coins use three different dating systems: the NS and SE systems before 1888AD, and the Vikrama Samvat (VS) system after. (This is an oversimplification.) To find the AD date from the VS date, subtract 57 years.
Coins of Tribhuvana Bir Bikram run from 1932 to 1952 AD, which corresponds to 1989 to 2010 VS. Similar coins date as late as 1992 AD, or 2049 VS.
We can give you a general idea for value but, because the market is fluid in Nepalese coins, these are really best guesses.
50 PAISA (25 mm diameter, 0.143 troy ounces silver)
worn: $3 US dollars approximate catalog value
average circulated: $5
well preserved: $8
fully uncirculated: $10
50 paisa dated 2005VS are more rare; multiply these values by ten
50 paisa dated after 2005VS and before 2011VS are more common and contain only 0.059 ounces of silver; divide these values by two
50 paisa dated after 2010VS are made of copper nickel and contain no silver, values are low
50 paisa dated 2007VS are rare and catalog for $175 in average circulated condition
50 paisa dated 2012VS are rare and catalog for $100 in average circulated condition
1 RUPEE (28 mm diameter, 0.285 troy ounces silver)
worn: $7 US dollars approximate catalog value
average circulated: $10
well preserved: $12
fully uncirculated: $20
rupees dated after 2005VS and before 2011VS are more common and contain only 0.119 ounces of silver; divide these values by two
rupees dated after 2010VS are made of copper nickel and contain no silver, values are low
rupees dated 2012VS are rare and catalog for $100 in average circulated condition
You must apply the concepts shown on our Terminology page to convert the catalog values on this page to actual buy and sell values.