In 1-quart nonreactive saucepan, stir blueberries, raspberries, strawberries, granulated sugar and orange juice. Heat to boiling over medium-high heat. Reduce heat to medium-low. Cook about 15 minutes, stirring frequently, until mixture cooks down and thickens. Remove from heat; stir in chia seed. Transfer jam to medium bowl; cool 30 minutes at room temperature, then refrigerate at least 30 minutes until cooled.