What a beautiful piece! Clearly what you have, Martin, is an award medal from the Calcutta International Exhibition (also called the Calcutta British Exhibition) held from December 1883 to March 1884 in India. According to WorldExhibition.org, there were one million attendees. Queen Victoria was well into her 60+ year reign at the time, and her portrait looks exceptionally striking on this medal.
The example in our picture is in very good condition, and is therefore worth a substantial amount. Remember, Martin:
NEVER CLEAN A COIN. CLEANING RUINS VALUE.
The pictured medal comes from Noble Numismatics in Sydney and Melbourne. Thanks, Noble. It is a beautiful item.
To get an estimate of value, consider that Noble auctioned the pictured medal for $300 US dollars during 2008. If the condition were worse, the value would go down substantially. The $300 price tag is an auctioneer's hammer price. It does not include seller's fees or buyer's fees, which usually run in the neighborhood of 10 to 30 percent. Similarly, if you were to sell this piece directly to a collectibles dealer, he or she would probably pay about one-half of the retail price. The mark-up keeps the dealership solvent.
Another specimen was sold in October 2013 by Dr. Busso Peus for ?110 EUR, or about $150 USD. It was in a worse condition, with a detracting splotch on the reverse.
More recently (July 2016), a medal in similar condition to the one in our main image was sold by Noble Numismatics for $240 AUD, or about $180 USD.
There is a picture of a medal with the 'Awarded to' area engraved at the MuseumVictoria.com.au web site.