The tilma of Juan Diego has been the subject of much modern research. The tilma, woven out of coarse cactus fiber, should have disintegrated after 20 years, but although over 500 years have passed the tilma is still in perfect condition. The pupils of Mary in the picture reflect the Indians and clergy present at the time of the first revelation of the image. No paint was used, and chemical analysis has not been able to identify the color imprint. Additionally, studies have revealed that the stars on Mary's mantle match exactly what a Mexican would have seen in the sky in December of 1531.