1 Corinthians 15:7

After that, he was seen of James; then of all the apostles (KJV)

Then: It's difficult to tell if this is basically a chronological accounting or a comprehensive attempt. He already mentioned "the twelve," but the apostles include more than just those, i.e., Barnabus, Andronicus, Junia, James Matthias (Baker, p. 215). It is the only record of James seeing Christ singly. Baker also notes that this is the brother of the Lord because James, the disciple, would have been included with that group of people. Also, Jesus' brothers, all skeptical, would need a personal talk with him as risen.

Now: It is truly a mystery why some are able to hear (read) of Christ and believe while others need personal, historical experiences in order to know that Christ is the son of God, a risen Savior and one on whom we can depend. And once we believe, telling others who he is, adding our personal witness, and praying for others to know him is our joy. When the confirming power of the Holy Spirit moves into the lives of those we love dearly, joy spreads.

Extra Source: Cornerstone Biblical Commentary 1 Corinthians (William Baker), 2 Corinthians (Ralph Martin & Carl Toney), ed. by Philip Comfort. Carol Stream: Tyndale House Publishers, c2006.