Instruction: Parse the product information to locate the target attribute, and then provide the extracted value of the target attribute and its source in the output, specifying None if the attribute is not present.

Input:
Product title: Opal Stud Earrings with Diamonds cin 10K White Gold
Product description: Beautiful white opals, the birthstone for the month of October, shimmer from the center of these brilliant studs. These earrings feature 10 karat white gold and a dazzling diamond halo.
Product feature: FREE Shipping on ALL orders over $100 from Gem & Harmony! (Otherwise pay only $0.99 shipping on orders under $100), Elite customer service offered by Gem & Harmony - Shop with confidence!, FREE Expedited Shipping UPGRADE on all orders over $300! Simply select EXPEDITED shipping at checkout and the charge will be FREE when cart value is over $300!, 30-Day Money-back Guarantee if you are not completely satisfied with your order, Free Signature Gem & Harmony Gift Box, Product Dimensions: 0.2 x 0.2 inches, Shipping Weight: 3.52 ounces, ASIN: B01B34GT0Q, Item model number: 01CCG226712OPW, Date first listed on Amazon: January 26, 2016, Average Customer Review: 3.0 out of 5 stars 1 customer review
Product brand: Gem And Harmony
Target attributes: Silhouette
Answer: attribute: silhouette
value: stud
source: product title
attribute: silhouette
value: studs
source: product description