Diamond Price Explorer

The Problem

• Diamond pricing is opaque to non-experts.
• Carat, cut, and color interact in ways that are hard to reason about.
• A quick interactive estimator helps shoppers sanity-check prices.

The Data

We use the diamonds dataset shipped with ggplot2 — 53,940 diamonds.

library(ggplot2)
nrow(diamonds)

## [1] 53940

summary(diamonds$price)

##    Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
##     326     950    2401    3933    5324   18823

The Model

A linear regression of price on carat, cut, and color:

fit <- lm(price ~ carat + cut + color, data = diamonds)
round(summary(fit)$r.squared, 3)

## [1] 0.871

The App

• Sidebar: slider (carat), radio buttons (cut), select box (color).
• Server: predict() on the fitted model, updated reactively.
• Main panel: predicted price + a scatter plot showing where your diamond sits.

Try It

• Live app: https://alexbrijo.shinyapps.io/diamond-price-app/
• Built with shiny, ggplot2, and knitr.

Thank you!