Exhibit 23.1
CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM
We consent to the incorporation by reference in this Registration Statement on Form S-8 of our
reports relating to the financial statements and financial statement schedule of Blue Nile, Inc.
(the “Company”) dated March 3, 2009 (which report expresses an unqualified opinion and includes an
explanatory paragraph relating to the Company’s application of Staff Accounting Bulletin No. 108,
Considering the Effects of Prior Year Misstatements when Quantifying Misstatements in Current Year
Financial Statements) and the effectiveness of the Company’s internal control over financial
reporting dated March 3, 2009, appearing in the Annual Report on Form 10-K of the Company for the
year ended January 4, 2009.
/s/ Deloitte & Touche LLP
Seattle, Washington
March 3, 2009