Ironically, JB doodled this exact necklace in school, which was recovered by police. Not saying that proves anything one way or another, simply pointing out the irony and perhaps illustrating that the blood speck that was "similar" to JB makes sense, assuming the necklace was obviously in his possession at least one time (when he made the drawing).
Source (another excellent site on the case by the way): West Memphis Three Murder Damien Echols Jessie Misskelley Jason Baldwin Michael Moore Christopher Byers Stevie Branch WM3 Robin Hood Hills Paradise Lost West of Memphis WOM – thewm3revelations
Source (another excellent site on the case by the way): West Memphis Three Murder Damien Echols Jessie Misskelley Jason Baldwin Michael Moore Christopher Byers Stevie Branch WM3 Robin Hood Hills Paradise Lost West of Memphis WOM – thewm3revelations