The agency picked up the brief with the aim of boosting traffic to the jeweller's website during the run-up to Christmas.
UK-based Astley Clarke intends to extend its web reach to the US and Middle East through its latest search marketing efforts. The jeweller currently relies on the UK for the majority of sales.
Steak Media runs paid search advertising for brands including British Gas, Enjoy England, Time Out, FCUK, JJB Sports and Swiftcover.com.
The agency has been engaged in a recruitment drive in recent months following a cash injection from VC investor Beringea earlier in the year.
Last month, former United London managing partner Robert Campbell joined Steak Media as a non-executive director.
Meanwhile, Peter Suchet, the ex-marketing director at digital media agency I-Level, joined Steak Media in October to head the agency's marketing operations.
Steak Media is also set to join the Institute of Practitioners in Advertising as part of a move by the trade body to set up a council dedicated to search. As well as running search advertising, Steak Media has increased its offering to include affiliate marketing and display ads.