Hong Kong QV 30c used stamps, both cancelled by C1 obliterator in blue. C1 obliterator is rarer in blue than in black and only one cover is
Hong Kong QV 30c used stamps, both cancelled by C1 obliterator in blue. C1 obliterator is rarer in blue than in black and only one cover is known (dated 13 Oct 1875, Ex- Ishikawa and Burghard, now in the collection of Hong Kong Museum of History) which made used stamps the only way to acquire this cancellation.香港維多利亞女皇像30仙舊票，銷C1藍色殺手戳。藍色之C1殺手戳較黑色少見，實寄封存世已知僅有一件（日期為1875年10月13日，石川良佐及Burghard舊藏，現為香港歷史博物館集藏），故舊票成為入手之唯一途徑。
